The Simple Question that Stumped Everyone Except Marilyn vos Savant 

I have a question, if there are three doors, there is a 1/3 chance of winning, but if there is only two doors there is a 1/2 chance of winning. There is a 50-50 chance you will win, so what’s the point of changing. The first door you picked might be correct. Plus, isn’t it human psychology to give the person who did it correctly to pick something else so they go wrong?

The chart at 3:40 is wrong. Only getting a car is considered winning

I had to watch this video like ten times. I bet it could get into some mathematic gibberish. If you add them all up to 1, make a pie, and then take away 1/3, you are left with 2/3 of pie and 2 doors to give an equal slice to. You'd split them into 1/3 each, counting the total they came from, which would be half of what was left while using their logic. Help.

​@@vaibhavk1342 does this make any sense? I had to watch this video like ten times. If you add them all up to 1, make a pie, and then take away 1/3, you are left with 2/3 of pie and 2 doors to give an equal slice to. You'd split them into 1/3 each, counting the total they came from, which would be half of what was left while using their logic. Help.

@@pheresy1367 That is why this question is sort of like fake news. no normal person accepts it. after the goats are shown its 50/50 of the last 2 doors. no normal person could think that in the final choice of the 2 doors THAT THEY SOMEHOW LOOK AT THE PAST.

Wow, that's amazing.

She probably picked up the bill knowing there was a 100 % chance you would take it from her 😆

If youre the smartest person in the room? You're in the wrong room. Lucky you. I'd love'd to speak to her for just few minutes.

You too?! The most remarkable thing about noshing with her is how she can pass things around the table telepathically. Oh, deary, I do hope she regaled your party with such feats. She even levitated all of us home after the dinner. Brilliant woman, that.

@@roberttyrrell2250 So what you're saying is, that she's always in wrong rooms?

I had to give you a thumbs up, not because it was correct, but because it was damn good.

However, on a show that happens every week, the viewers would soon get wise if the car was always behind door 2.

lol!

@@mandolinic I think statistically, door #2 was more often the right choice. Everyone playing along at home would always yell DOOR NUMBER TWO! So the trick then would be to guess door #3 and see if he shows you a goat behind door #1. If he does, you got the historical statistics and the live probability on your side.

They were schroedinger's goats

True

Around here, when a vocal 50/50er finally figures it out, a typical response is to delete the thread so there is no evidence they were wrong. What's the opposite of humility?

​@@Hank254hubris?

Or don't respond like a prick in the first place.

"I am most impressed with the math professor who publicly admitted his mistake." Me to. How can you get a PhD in math and fail so hard at a simple probability problem?

Too bad idiot Vos Savant failed to acknowledge her profound error. Too bad too those MIT profs are shown to be idiots twice over. It's a new game. 1 in 2 chance, 1:1 odds. Though Hall does not say it in these words, he asked this: "There is a car behind one of two doors. There is a goat behind the other. Which do you choose?" It is irrelevant that Hall phrased it this way: "Do you wish to stay on Door 1 or switch to Door 2." Vos Savant is an idiot as are those MIT nitwits.

@@DonLicuala It is almost a psy op her exist right down to her name "Savant".

What? My comment has nothing to do with her achievment, its about the humble gentleman who knew how to apologize. I have no obligation what so ever to list anyones achievements, please look for an argument elsewhere.

Vos Savant is wrong still. She will be wrong even after she dies. She has applied conditional probability math skills but from the wrong premise. At the initial door opening to show one goat, the probability is 0%, odds, 0:0, chances 0 in 0. The contestant is not trying to avoid two goats, but rather only one. The probability of winning from the moment when an actual positive probability can be calculated, i.e., from the moment of two doors, is an equal probability of 50% to each door, as there are two options and no further information available. And that is the only solution, the correct answer to the Let's Make a Deal Problem (LMADP). An alike problem "The Monty Hall Problem" (MHP) is a pseudo-realistic problem derived from the Let's Make a Deal Problem that illustrates an application of conditional probability assuming a contestant can win on Round 1 but does not and gets a second chance with updated info. While the analysis of the MHP is self-referentially correct, it is inapt for the LMADP, which presents a contestant with a choice from two options, two and only two unopened doors. The MHP would be appropriate if and only if there were three doors and a constest could win right away from picking the right door of three. Yet, in the LMADP, there is no deal when there are three doors. The Rules to the LMADP are these, which are different from the MHP rules: 1. Say the name of the door. It does not matter because we're not revealing it. your odds of winning are 0:0., probability 0%, 0 in 0 chance. 2. Carol, from the doors not picked reveal a goat. 3. There could be a goat behind your door or a car. What door do you wish to name? You can name the same one as you did previously. You have a 1 in 2 chance, or 50% probability with the odds being 1:1 of getting it right. Once you pick we reveal the goat door first if you picked the car, the car door first if you picked the goat.

The question which wasn't answered here is that "why would the host open a door if they had the wrong option"?

I know, and I hate it, we need better people in this world!

It doesn't matter what people think. it is what it is

in your imaginary world? sure

@@toxic_narcissist wdym?

@@toxic_narcissist without more context, your comment means nothing.

This is the only thing I understood

@@thecoweggs i know right

I love goats. I can no longer afford to run a car... :-)

This video presents the presenter as being on your side, "helping you out." This is a bad assumption unless they're truly your friend, which is unlikely. Haven't you seen Slumdog Millionaire? :-) So when they select something to lure you away from your initial choice of door, as an option for you, it can be a decoy, not the real deal. After all, if you chose that door first, it would have the same amount of probability from the standpoint where the presenter may not be on your side. IQ is racist pseudo-science. Savant in name only. The reason Mongoloids in Singapore and elsewhere have the highest IQs is because their youth was sacrificed for the god of money, and they did parroting memorization including of formulae which help in many IQ tests, at least to be used to patterns. This is why a Papuan tribal won't beat them: The tribal isn't dumber; just not used to those types of tests 'cause they DON'T NEED TO BE. IQ tests use a one-size-fits-all appraoch, which is stupid, and proves IQ is stupid. If I took an IQ test, it was probably disguised as some standardized test in Florida long ago. I don't believe in that shit, so I refuse to participate. It's just like DNA testing: Different testing companies give different and contradicting results, so they're all scams. If you are truly smart, you'll know better than to let others tell you how smart you are, when those others are self-entitled narcissist establishment people trying to dictate your mind.

@@scintillam_dei very very wrong

it's 99% of being wrong and then the switch is 99% of being right. it's reversed. revealing the doors does not give any hint on your first choice, so it's still 99% and not 98%

99%.

(Car is prize). Let’s say the chooser did not pick a door at all. The chooser does not know whether there’s a car or a goat behind ANY of the three doors. The host, however, knows what’s behind each of the three doors (ALL). They both stand in front of the three doors and the chooser does not pick anything at all. Now, the host reveals that there is a goat behind door #3. That eliminates door three as an option for the prize. Bye-bye! Now there are two doors left. That means there’s a 50% chance that the car is behind either of the two remaining doors. The high IQ vos Savant is declaring the idea that the chooser having originally simply “THOUGHT” (chosen) of what the winning door might be before the host opened door 3, CAUSES the remaining 50/50 ratio to change. To me that sounds like she is either not that smart OR OR OR, she is pulling ideas from things like quantum theoretical physics such as the “double slit experiment” and such. Like, the theory that when trying to guess if there’s a cat in the box, actually there is no cat in the box until you open the box, then it either does or does not manifest, because our reality is made up of potentialities rather than actualities, until they are “looked at” or measured -to be more precise (that’s how the theory goes, which is pretty much proven at this point). So, I think she needs to clarify what level of accepted reality or physics she’s pointing to in advance of her explanation, because the description of the solution by her and this video is implying that the chooser’s THOUGHTS (manifested as a supposed “choice” or predisclosed “guess” of where the car might be, affects the outcome. It’s similar to me arguing with you that nothing actually exists because atoms don’t reeeeally touch each other and sub-atomic particles are only energy in their smallest form. In a physics class that discussion or answer to a topic might be appropriate, but in an online forum about whether I have one or two cups on my table , it isn’t necessary appropriate. We obviously have different “levels” of reality we are talking about. The one to attend to needs to be disclosed in advance because she is LITERALLY saying that the difference between whether the chooser specifically made a choice (THOUGHT), or not, before the process of door openings began, AFFECTS the outcome. That’s not really actually fair according to the standard discourse. An online basic forum is not a quantum physics class. Thanks for reading.

PS. This might be going too far, but, it also makes me think she’s purposely trying to mess with people’s heads. lol. It worked ‘cause even the PhD’s were crying but funnily enough what they missed is she subtly didn’t disclose to them all the facts of the game. If I tell you we are living in a video game, am I lying? If I walk away and leave all the PhDs to fight about it, then they cry and appologise, am I smart?? Hell yeah! Am I right? Not if the rules of said game weren’t disclosed. lol. Sounds a bit narcissistic IMO. 🤭

@@SolutionsWithin You obviously did not understand the problem and are not smarter than Savant lol. Not picking a door first is different than picking a door first, because then the host cannot pick this door and has to chose between the other 2 only. You picking a door eliminate this choice for the host. That's why it becomes a 1/3 - 2/3 and not 1/2 - 1/2

there's nothing to understand. She considered each door a floating variable. Each door is in absolute matter of fact, a constant. So there is no means to transfer probability from one door to another. Once the 3rd door is opened, there is no more question of what's behind door 1 or door 2. It is either a goat or a car. The feeling that you have a 33% higher chance when switching is based on the original probability you had to correctly guess between 3 doors. Once the 3rd door is eliminated you have a completely new expression. And the probability between two choices is always the same. Stay or change your mind, implies that the previous variable is still in play. It is not. You are not "switching", you are again choosing. The difference between the two choices is 50%, probability is recalculated at every choice.

@@ZennExile incorrect.

@@vladimirdemirev4948 the reason why door are grouped is because they are different. One is the door you picked, the other two are the doors the host has to pick from. Your grouping doesn’t account for that. The professor admitted they were wrong because they were wrong.

@@vladimirdemirev4948Say we take a bag with ten marbles in it, one orange and nine white. Whoever gets the orange wins. You pick a random marble from the bag and I then take the remainder, open the bag and select a marble, discarding 8 white ones. Who is more likely to be holding the orange marble. Clearly the person who knows where the prize is will have a better chance of selecting it.

@@morbideddie well, I guess I am wrong. Seeing the 100 doors example changed my mind. I will go with the excuse that binge-watching RU-vid videos on different topics trains you to react first, without giving much thought ;)

I always tell my kids four things:. 1) you panic, you die. 2) stupidity kills. 3) never do anything for which you will have to apologize for later. 4). And) (a biggie),.never take up a habit you're just going to have to break later on.

@@sheilalopez3983 Good word

Seemed to me "they" were sort of picking on her for not using the "math stats" as they did ? Oh, of course; now let's hear it for the "Intelligence of Creative Thinking!?" It seems THERE ARE different "kinds" and "types" of IQ " Tests." Experience and Education , two possibly different types ? So we should be also asking WHICH IQ Test did Marilyn excel in, or on ? MISSING FROM the video; Does this lady write and speak in both German and Italian ?I've always felt there is an extreme indication of high intellect in regard to peoples' abilities TO express themselves in foreign languages ?Seems there is a certain "type" or "kind" of logic it seems in learning to "relate " foreign language to one's own ability to speak and write in their native language ? It appears Marilyn 's " (by assumption?) that Marilyn had TWO "Native languages" yes ? Her opinion of "public schooling" holds great merit. I remember a question required to be asked on a high school test , was "Who were the Phoenicians ?" The ABCD Answers included the answer " Venetian" . Most admitted later that they all misunderstood the word Phoenicians because they were all more "familiar" with Venetian Blinds, than historical terms of peoples and places! (Ha Welcome to American World History 101-we (all) need to repeat that one!?) Which btw lead to my last question (for you or Marilyn, ha ?) Is the inability to "spell" properly (in any language/especially ones native language ) indicate ignorance ?Duh...As a retired teacher, I submit I've become dependent on the Google Gargoyles ' offers for correction, which often just doesn't exist. The robots tell me I've misspelled something, yet/while, offering no options with which TO correct it. Good at Questions; Slow at the answers. Anyone ? "I Ain't no Middleman" Fred Gold & Lynda Faye Copyrighted 2016 by LyndaFayeSmusic@gmail.com or Yahoo, if censored for using the word " God" too often?

I don't because they made her same mistake she did when they followed her idea.

@@gerardcote8391 ? Please explain! Thanks!

Yup. Easy-peasy... yet to complicated for people thinking "two doors equals 50/50".

@@max5250 What I missed at first is the fact that he will never pick your door, so now you get lots of information about the remaining two doors.

no it's not like you understand it, if we go by your understanding the door you switch to would have a 100% chance of winning

@@oussama1811 No you lose if you already have the car. You have the car 1 our of 3 times.

Your assumption is mistaken. While it is true that 2 out of 3 times you have the goat before Door 3 is opened (or 4 chances out of 6), when he reveals the goat in Door 3 then there are only 4 possibilities left, not 6. So at the point that he reveals the goat you only pick the car 2 out of those 4 remaining times if you switch doors.

@@user-ej9nl1ng9d lol - same principle

@@user-ej9nl1ng9d I know - I was just putting it simple

@@user-ej9nl1ng9dMost of the people who argue about it can't read a table. Many can't even follow John's simple logic. The biggest problem is getting them to realize 50/50 is wrong or they don't even listen to explanations of the right answer.

thank you - that is a good explanation the key is that *the host always eliminates a losing choice* the odds that the original choice was correct don't improve but the odds that the remaining non-eliminated door is correct do increase it is easier to grasp for most people if the door count is say 10 or 20 or some other larger number if all the choices are eliminated except the initial choice and one other there is a very high probability that the correct door is the one remaining door (the one not eliminated)

You explained it in simple to understand language. In fact, the best articulation!

But you are wrong.

I don’t understand how the extra odds don’t also add to the door you chose. They’re both still closed and options.

@@BasedGodGotenks Look at the 100 door example. The chance you chose the correct door from 100 doors is very low. The chance the winning door is amongst the other 99 doors is high. Now remove 98 of those 99 favourable doors and the remaining one has a very high probability of being the winning door. Now if you arrived at the game late and missed the above process of elimination and just had 2 doors to choose from then your chances would be 50/50 because you do not have the information that points towards the more favourable door.

it doesnt make sense still fuck, how, every door has a 1 in 3 chance of being the car, revealing one door doesnt give the other door a higher chance as it was predetermined beforehand, its still 1 in 3, it cant just change cause you revealed the other door fuck like ik it makes sense to some people but it doesnt to me. EDIT: This is how i see it, in the start you have 1 in 3 chance, after goat reveal, you are left with 2 doors, 1 has a goat one has a car, so you are back to beginning, when deciding in that moment, you have a 50 50 chance you will get it

This is an excellent way of looking at it

That is brilliant. And the only way to lose the switch would be because you beat the 3 to1 odds against you when you first chose. So it's always (3 to 1 against you) vs (2 to 3 for you by switching after the goat reveal). (Ooops, I think my "further clarification" only served to complicate). ;-)

That is a great way to look at it. It takes a certain personality, I think, to be encouraged about odds of 2/3. Chance is not something you can predict -- it's chance. This is the difference between stochastic (your statistical analysis) and random (what actually occurs). There is a world of words and ideals and a world of things and occurrences. Some people love to argue over words and ideals, but we each may go home with a goat. Or a car.

Unless you did pick the car on your first choice....... It's literally a 50/50 chance. You either change your answer or you don't, and you either win or you lose

exactly. or pretend there's 100 doors. now you get to pick either (a) one specific door, or (b) the combined total of any 99 doors, where if there car were in any one of the 99 doors you'd win it. would you pick choice (a) or (b) ? okay now instead of 100 total to start with, let's do 3 total to start with.

Appreciate that! Are you noticing a quality in recent videos from 2024 compared to older ones?

@@Newsthink absolutely, from the audio to the graphics. However, your story telling has always been unbeatable, so no difference in that to be honest.

"Way less" is pretty vague. It would be better to say "half as likely" which is accurate.

I've always thought that's the simplest, clearest way to look at it. Don't try to figure out the probabilities. Just list the possible outcomes. It's a small enough data set that it's not a big deal to make a comprehensive list. There's only three places the car can be. There's only three initial choices you can make. And there's only two second choices you can make. That's 3 x 3 x 2 = 18 possible scenarios (9 scenarios for staying and 9 for switching). If you stay, there are 3 ways to win and 6 ways to lose. If you switch, there are 6 ways to win and 3 ways to lose.

well If you watch the show is oblivious, you can also assume how the show would b er if you havnt watched it. But still the author of the video has a bad taste.

ohhhhhhhh ok this makes sense now

Oh this makes sense now. I was under the impression that the game host always open door 3 regardless. Which is why I was confused at 3:20, when the table showed scenarios "game 3" and "game 6" having a car behind door 3 which made no sense to me at first so I excluded those scenarios. But I understand now, thanks!

Came here to say this. In video it sounds like host might have just chosen a door at random, and it happened to have a goat. It should be stated that the host will NEVER open the door with the prize when he opens his own door after the contestant chooses.

Well if the host would pick the door that was chosen by the participant and there was a goat, there would be no question of switching the choice of doors. And if it was one of the other doors and there was the car, the same thing applies. So in my opinion it's self explanatory

"If the player initially guessed the prize door(a 1/3 chance) and they switch they lose. If the player initially guessed a non-prize door(a 2/3 chance) and they switch they win." I first heard this riddle in the 2008 movie "21", and until today I never understood why switching doors after the reveal of a goat would increase the chance of winning, but the way you phrased it made it click for me, so thank you, i finally get it :)

that is probably the only explanation i've ever heard for this that makes sense. because no other explanation, even when presenting empirical evidence, actually draws that connection.

For me the biggest mystery is why your explanation is not immediately obvious to everybody. Lots of people deny it, even after someone carefully explains it to them....

@@tonybrowneyed8277 yea I think they're missing the difference between the host revealing a random no prize door, and the actual Monty hall rules. That would give 50/50 odds and the Monty hall game looks the same on any individual round. But the host not being able to reveal the same door as the players first guess completely changes the odds and the nature of the game.

" If the player initially guessed the prize door(a 1/3 chance) and they switch they lose. If the player initially guessed a non-prize door(a 2/3 chance) and they switch they win." omg i finally get it tyy

probably in the 125 - 150 range.

@@arandomguy46 wtf

@@epicmorphism2240 The creator probably didn't know. It was just a game. Maybe after decades of hosting the game they ended up with a "gut feeling" that is better to switch but they probably thought it was 50% too

@@andressoto739 i was commenting ln CRB‘s ridiculous comment

noobs create problem pros solve it

ADHD compounds this problem big time. Someone with ADHD is borderline incapable of learning things that don't interest them at all, yet I believe it becomes an advantage when we really are interested in the subject because we can devote hyperfocus to it.

@@jasondashney no kidding, I'm just a teenager, and yet I can understand, and I know about, many things that adults, even in my field of interest often don't know. I was let to go my own direction, and I'm great at it!

I believe it. That's great you understand that about yourself. Keep that in mind when you decide what to do with your life.@@Metal_Master_YT

@@jasondashney thank you! :D I also have ADHD, but I feel like I can "tame" it and use it to my advantage, kind of like you said.

This is interesting to hear. The school-system bothers me alot. For me, voluntariness is essential for sustainable learning.

Exclamation?

No you didn't

😂

I think this one is better. (Monty Hall Problem (best explanation) - Numberphile) because it emphasizes the importance of Monty knowing the location of the goats. I think lots (if not most) people get lost because they think it's a completely random situation.

The problem is that the question is flawed or rather, the interpretation of the question is flawed. The assumption here is that the player has to pick the first door. The second assumption is that the host will filter out all the bad doors and this would mean the host would purge the door you picked which was wrong which makes the 100 doors example useless. One glaring problem is that nobody accounted for process of elimination as even though the probabilities started at 1/3, the host removed one bad apple and now it's 1/2. One bad apple will always be eliminated and if it's going to be eliminated, it doesn't exist. Now, in the actual tv show game, the option is only offered by the host if the player's first choice was wrong.

@n3__ The problem is well.... No offense, but either you don't understand it, or you are not expressing yourself well. Just for the sake of discussing the problem, we say: "let's say you picked door #"1.In the begining, we don't know which one has the car. It sounds like you don't understand that the host did not randomly open a door. He intentionally opened a goat door.. We already knew that among the two not picked there was at least one goat door. So the host did give us any useful knowledge. The odds remain 1/3 Vs 2/3. This has been verified many times with computer simulations. It always comes out with the same odds.

@@DennisMSulliva Exactly, first "bait round" happens, the player has to select a door and the odds are 1/3 for getting the car and 2/3 for getting a goat. This round is of no consequence whatsoever which is why it's a "bait round". Then for the second round, the host reveals the contents of one of the unselected doors and reveals a "goat door". The manner in which the question was asked, the player has no clue if the first door they selected had the prize or not. Therefore they're re-picking one door again. So, after realizing that the number of elements are different from the first round, the probability for this round has to be re-evaluated by taking the new elements into account. For this round, there are two doors (unless the player is stupid enough to pick the already revealed door) and one of them contains the prize, the other one doesn't. So the recalculated probability for winning the prize is 1/2 and not 2/3. 2/3 only exists if the probabilities aren't recalculated after the number of elements have been changed.

@@N1c0T1n3__ NO, NO, NO. That is mathematically false. If you can't see the logic of it, be advised, it has been verified with computer simulations. You are the one who is recalculating the probabilities. You had a one third chance that you were right, on the first choice. That one third choice is not to be recalculated. It is still the case. You already knew there was at least one goat, among the two not picked. You gained no useful information by the reveal of the goat. I don't claim to be superior. It took me a long time to get it.

"instead of realizing that it's making a new selection with better odds" It is not making a new selection with better odds, but swapping your lower odds for better odds.

@@max5250 Now I get it, thanks max ; )

@@anthonydenn4345 Welcome back dude.

I still don’t understand why switching will increase your odds of winning. If you take away your first selection, meaning you never made a choice, are you still going to choose the one out of the 2 doors that didn’t get eliminated?

@@jacobcutrer Switching increased odds of winning because host get to pick from two doors therefore, he gets a door with a cat twice as often than player does. When he opens his door with a goat, we know which door holds a car twice as often as the door initially picked by the player.

Weirdly that does make sense.

Exactly. The thing people don't seem to understand is that the host must open one of the two wrong doors. He cannot open the door with the prize in it (this defeats the point of the game) or your door (which would render the decision obvious). If the host were randomly opening doors (and could open your door or the one with the prize in it), then this wouldn't work.

@@user-wu4bo1hz3p what if not randomly opening door? Just not opening door that is yours and.prize ?

@@yuquoint6633 Huh? That's what he's doing, which is why it works.

@@user-wu4bo1hz3p Ah finally i get it, thanks for explanation.

good explanation. Perhaps it's easier to just focus on your prize? It's easier to pick wrong, and if you stay, you would end up with the wrong prize because the prize behind your door never changes.

Couldn't it also be interpreted as him trying to sway you though? This has too many variables. For example, what if I already picked the right door and he could have just chosen either 2 or 3 and it wouldn't matter. What if he's trying to discourage my current answer by making me second guess myself, which often results in switching doors? At the end of the day the idea that switching increases your odds is reliant on the idea that you didn't pick the right door first. And that he could have just picked either door because neither and the prize and he didn't have to avoid it.

Not to mention. If I've already picked the wrong door. Then what does he stand to gain by giving me the chance to switch? He has absolutely no motive to give me a second chance and not only that. But narrow down my choices and increase my odds of winning. It's just not a smart move to make and only a fool would do this. His smartest move would be to try and sway me away from my current decision by making me second guess myself.

ALWAYS choose door #3

The way I look at it is he initially had a 1 in 3 chance of being right with door #1. After door #3 is revealed he now has a 1 in 2 chance regardless of whether he chooses door#1 or #2. Revealing door #3 gives no specific information about either of the other 2 doors. So I agree with you. In my mind they have neglected to revise the chances of door #1 being correct after door #3 is revealed.@@trapidtrap2612

It's the only affordable way for most.

The 1948 and 1988 encyclopedia sets of the "Book of Knowledge" were my favorite source of learning. I LOVED them! I always checked the Public library a lot. My fiction was mostly from Silver Age comics that helped me much with my art. I loved studying electronics. I didn't need school for any of that. Now days, Professionals seem to get their credentials out of a "Quaker Jack Box."

I prefer self-teaching.

@@karangupta1825 Yes. Expand your passions and have creative hobbies.

"The book of knowledge" was very pictorial and was suited for all ages. The simple facts of the topic were clearly explained and the information became gradually more complex for when you are older. It was laid out like the internet with many links in the index's. There were plenty of do it yourself projects. I build my first radio from the 1948 book at 11 and it was fantastic!

Omg, I was just about to write the code after seeing this random puzzle. Unbelievable conclusion.

Yeah I was around ~15 when this happened and also wrote that program at the time, though I either had no idea what was correct or was pretty sure she was. Don't remember which!

I still don't understand how. You don't know what is behind the two closed doors . So the probability for you ( any subject) is 1/2 .

@@siddharthshekhar909 the chance of your original guess being correct is 1 in 3, no matter what door you guess, the host can open an empty door, thus your original odds of 1/3 are not changed by the host opening an open door. By switching you end up with 1/2

@@siddharthshekhar909 EXACTLY!!! This is what I said. I absolutely could not believe it! This is why I wrote the program! I wanted to prove them WRONG. There is no logic to their conclusion. But as it turns out I was wrong!!! I still can't explain it. But the computer doesn't lie. I am a software developer with 30 years of professional experience. The program took an hour to write. I had to run it like 10 times before I could believe it. I still can't explain why it works. Don't feel bad. There were MIT professors who felt the same way you and I did. And she is the smartest person alive so I wouldn't sweat it if you don't understand why. I don't either.

@@johnp.johnson1541 Assume you stay with your first pick. If your first pick is Goat A, you get Goat A. If your first pick is Goat B, you get Goat B. If your first pick is the car, you get the car. You only win 1 out of 3 games if you stay with your first pick. Switching means the opposite. It's just basic math/logic kids understand. Sadly, it's far too hard for johnp.johnson1541, the idiot among idiots, and his parents, the ultimate idiots.

"Host always opens one of them, so that 2/3 chance is now accumulated in the last door." Probability is always "accumulated" behind one door, since a car can be behind only one door, not two of them, and a host, who can see content of the doors with his own eyes, see which door holds a car.

Yup, it really is that simple but people still get locked in to 50/50 for some reason and hold on to it like a pit bull.

You are not correct, and I will explain to you why, very simply. You correctly differentiated between Goat 1 and Goat 2 in alternatives 1) and 2). In alternative 3), you do NOT differentiate between Goat 1 and Goat 2 by stating , "either Goat 1 or Goat 2" Alternative 3) should be, " If you chose car and Goat 1 is revealed, then switching would have given you Goat 1" Then alternative 4) which needs adding, "If you chose car and goat 2 is revealed, then switching would have given you Goat 2" Thus, in 1) and 2) switching works, but in 3) and 4) it doesn't. The result is 2-2.

Speaking of a pit bull...

@@Hank254 LOL!!!

@@georgebliss964 How can you NOT make a probability tree for this problem? Contestant pick car, host leaves goat. It has only ONE branch!!!

The people who believe it is 50/50 also think it is a joke.

@@Hank254yeah true

So switching comes down to thinking you made the wrong choice the first time. The odds change with the revelation of one goat. This is new information, not just "seemingly." The 1/3 or 2/3 scenario is now irrelevant.

@@diannemccarthy8685 No, the odds don't actually change, even though intuitively it may seem like they should. The way that I explained it above is the explanation that I personally find the easiest to understand, but if you don't find it convincing, just search for the "Monty Hall problem" in the search engine of your choice, and you should be able to find plenty of other explanations. When I first came across this problem a few years ago, I did a lot of reading about it myself, and I remember that there were even websites that allow you to play this game over and over, and they keep track of your win/lose record for when you stay and when you switch, and you'll see that over time the win percentage for switching averages to 66.6% while the win percentage for staying averages to 33.3%.

No, given the mind set of the Host, your chances of winning are BETTER than the problem suggests! Monty WANTS you to win! More fun, more excitement, better ratings, more sales of every item offered as a "prize" on the commercial, (ahem, "Show") The clue he gives you is that your odds got better after your first choice. Monty wants to make your chances of winning as near certain as he can, without being obvious.

@@lindsaymitchell9300 The show producers are always telling Monty what his next move should be. Anything that makes mo money.

@@zackreagin8384 The odds of the second door are increased after seeing the third door open, IF the game (which regulation I ignore) had the rule that BOTH a door must always been open AND the switch must always been offered. If showing an open door and/or the option of switching are not the rule of the game but may be decided by the host unpredictably, the host of the game might use the door open or the switch option as a way of deceiving the player, at times. That would not guarantee that switching to the other door carries more chances to win, in my opinion...

What I didn't realize was that the host obviously only opens a door different from the one I picked. So the odds remain 2/3 for goat.

Wow! That is the clearest way of describing the situation I've seen. "Stay with YOUR original 1:3 chance or take OUR 2:3 chance". The revealing of the goat was just a trick to make it seem as if it's become 50/50 to switch or stay.

What a great explanation, well said! It's obvious explained this way. I also like how Savant's analysis of all outcomes is so simple and really proves it, and yet the top mathematicians who criticized her didn't think to do such a simple analysis.

The host knows what is behind every door. The offer to change my choice is only given after I picked a door already. Obviously the host is trying to fool me. If I was given 2 choices from the start: pick a door, or pick 2 doors, the answer is obvious.

@@Tombecho If you think the host is benevolent: Switch. If you think he doesn't know where the car is but just got told where one goat is: Switch. If you think the host is mean: Stick with your choice.

You ever seen "Good Will Hunting?" Marilyn is basically that in real life. In the film there is a scene where Will is sitting in his professor's office and another professor walks in with a math problem he had been working on for a long time. Will solves it in a few minutes, leaving the professor highly embarrassed. This is what Marilyn did here.

@@JohnSmith-ys4nl We dont at all know that she did that. We dont know how she first reacted during the first time she encountered this problem.

Wow, air tubes! COMPUTERS!!! You sure did pick an unnecessarily elaborate method to test the MHP. You could just get a friend, sit down at a table, and test it 30 times, switching, and then 30 times sticking Recording results. Not satisfied, do it another 30 times. But in fact, the answer will become glaringly obvious long before the first 30 are done.

Way too logical. And a good way to think about it

But having a chance and actually proving you are correct is two different things. The car could have been behind door #1 and then everyone using their math ability to choose #2 would lose. Sometimes you need luck too. That is how nature works. You cannot predict anything definately. You can only guess.

@@edwardspencer9397 Sure this game depends on luck. But the chances to win are higher.

@@edwardspencer9397 that's why it's called probability. Out of three doors you will win one in three times if you stay with your original door. Out of 100 Doors you will win one in 100 times if you stick with your original door. It would be ridiculous to not switch unless you didn't want to win

@@edwardspencer9397 yes you need 'luck', but by always switching you will be 'lucky' 2 out of 3 times. Whereas, if you do not switch, you will be 'lucky' 1/3 times. Therefore, by switching you increase your 'luckiness'. Considering this, you may be less fortunate if you merely guessed at what to do.

You missed the whole point, which is that the quiz master KNOWS which door the car is behind. There is a 1/3 chance you got it right the first time. IF you got it wrong, probability 2/3, then the car is 100% certain to be behind the door the quiz master left closed.

Of course it is only 50/50.

@@slind3517 No, by switching it is a 98% possibility, when the original pick was 1% Perhaps you should actually study exactly what the 100 door scenario is before commenting

This 50/50 thing plays large in the history of the MHP, even among university profs. They are constantly trying to say that if rules said that the host would open that door at random, the game reverts to 50/50. It obviously does not.

Correct.

She cheated. Door 3 cannot be the car, so games 3 and 6 cannot be indicative of increased probability by switching.

@@polygontower Not after it is shown to be not have a car.

Now do the same, but assume you had selected door 2 on the beginning...

@@kelseysmart9472 the point of the game is that the host is eliminating one of the doors from the equation. From there you are choosing to switch your answer to the remaining door or not. Wether that is door 2 or 3 I do not believe matters.

Whether their retractions were praiseworthy depends on why they did so.

They probably wouldn't have written them to a man in the first place

Nah! They were more worried about how they would be received if they did not. The humble would not rebuke someone in public, as in a letter to the editor!

@@Elle-ht3km There was an extreme amount of sexism back then, and there still is a shocking amount now, but I don't think all of them were because she was a woman. At least a couple acknowledged that she still had higher IQ than them, and thought she simply made an obvious mistake. Even the cleverest people can do incredibly dumb things sometimes. I'm sure even Marilyn oversaw something really dumb in her private life at some point; and they probably thought it was one of those, but in public. They did grew heated to make sure she "corrects" the mistake and thought it was so obvious that it would severely undermine the population's understanding of probability. It was the exact opposite, but I can definitely see why they'd think it was a mistake. At least one of those letters was definitely sexist though, and knowing those times, probably a lot more. There's probably a lot of enchancement on it too, after having been told she's more intelligent than you are and then given actual proof of that statement. Thinking someone make a dumb mistake when you're both sexist and jealous would probably compound and get you extremely heated up. And then after she proves you wrong, and you get personal proof that you're dumber, you'd either get more embarassed and angry or you'd be embarassed and start respecting her.

#MeTOO

"Anyone who struggles with this has a very weak grasp of probability theory" so, paul erdös had a weak grasp of probability theory? i ask, because he as well struggled with the outcome.

Has anyone tested this? Like have 100 gameshow-like setups.

Nevermind, I realised how easy it is to test. Tried 16 ‘games’ and switch won 11 times while stay won 5. Pretty fun 😄

@@Dev1nci Try this one. Take a balanced coin. Toss the coin 10 times. Are 5 of them heads? Try tossing the coin 50 times. Did you get 25 heads? How many times did you need to toss he coin to get half of the outcomes "heads"? Try this one and report back. How many times did you have to play the game to win 50% of the games? Same result as 16 games?

@@techhie1302 I understand that principle but that's a different thing. You need to wait for a large enough pool for the stats to be visible :)

we already knew the ans if we watched other videos about that

I picked the 2nd door also. They said the car was behind #1 at the beginning. I listen very well

And this helped move mankind forward...how?

@@anti-apathy9715 1) Nobody said it did. It didn't have to. 2) Discouraging, patronizing women in the field of science, mathematics , etc. is not a trivial matter. (Although i do believe this could happen to anyone, but being a woman made it worse for her) Point is, such incidents prove to be a hindrance for little girls and young women who are already brainwashed by the society to think that they are not as good as men.

@@anti-apathy9715 ego trip

i just don't get it. if there are still only two doors wouldn't the odds be the same.

@@chestnut1279 Two doors left proves that you can either switch from your car to a goat, or from a goat to the car. The host could have simply asked you that same question when you first picked a door without doing anything else.

@@chestnut1279 I'm thinking the same thing. My understanding of this brain teaser is that changing your answer after the host reveals one of the fail doors is most correct but still not a guarantee as picking the first door was 1/3 vs changing the answer now making the odds 2/3. Its less likely you got it right on your first choice but it is possible. I think the logic of "two doors means equal odds" only works if the host revealed the door you picked to be the wrong door and you still had two options. But nothing makes me feel low IQ more intensely than brain teasers. I suppose the real question is do you think its more likely you got it right on your first try when you had three options?

@@chestnut1279 Yes. Sheep being lead.

If the contestant was given the opportunity to swap his 1 door for the hosts 2 he would almost certainly accept the offer leaving themselves with 67% chance.Don’t forget the host knows where the car is and has to open one of his which has to be a loser leaving the remaining 1 of his 2 which still has a 67% chance

Yeah, I caught that too

Imagine being born in the past millenium. How old you must be...

very common in the sciences.

historians are assholes for not starting with a zeroth century.

"So in the instance that you don't switch you have 1/3 chance of winning" Yup. A short cut for that scenario is to simply pick one of the three doors and open it since what's behind the door won't change no matter what the host does. Doing that it is easy to see why the first door has a 1/3 chance. The people who insist the doors have an equal 1/2 probability can never seem to pick one door out of the three and win the car half the times.

I get that but these fuckers in the show can lie :D

@@alenngkIt's not a real show... it is just a math question.

Kind of like people who post similar rants on RU-vid comment sections :) (not talking about you, btw)

indeed, it appears so logic to me that it's better switcch

At this point in my life I’m not lol. So many experts come with a strong sense of truth mixed with pride.

This is the issue she brought up.. educated doesn't necessarily equal smart.. and most often not.

@@Arthur.H.Studio what do you mean?

Thank you so much,your explanation made it make sense to me!

I find it amusing how people can be so naive. If the host reveals one of the door had a goat Then your Scenario B and Scenario C is EXACTLY THE SAME AS IT HAS 1 door with a goat and 1 door with a CAR!!!

@@shafin141 I guess you didn't fully understand the explanation. You have to think about the problem like I explained it, as in, including the odds of you picking correctly in the first place. Yes, after one door is removed, there's a 50/50 chance that the car is behind one of the remaining doors. HOWEVER. You have to take into account the fact that your INITIAL choice only had a 33% chance of being correct. Those odds have not changed. Try extrapolating it to 100 doors, and 99 goats. You have a 1% chance of picking correctly at the start. Now the host removes 98 incorrect doors, and you're left with 2 doors. It's still technically a 50/50 chance of there being a car or a goat, but you're not going to switch still? You have new information now. The host has essentially removed the majority of the wrong possibilities from the equation, so the odds of you now picking correctly if you switch have become 99/100, versus your intial 1/100 odds.

@@dchang8619 Sorry you are confusing yourself by believing that the initial 33%, 1/100 and 99/100 remain. They are gone now and dont carry over. Its now 50:50 and your original choice is just as likely as switching.

@@kenandlynboyle9300 it’s really not though. Try it yourself in practice, not in your head. Try switching 10 times, and not switching 10 times. See how many times you win by switching and how many times you win when you don’t switch. I promise you that you will win more times by switching. This has been mathematically proven, so there’s no real use trying to argue against it. Just try and understand why it’s the case.

"I don't understand why people have difficulty with this problem." Because they see two doors and instinctively associate 50% chance to each door. They also don't realize once you pick your door, you can't "pick again" with only two doors, since one door holds your previous selection, while other door holds the opposite of your door.

But that's my point. If it was intuitive for them to see 50/50 in their second selection, why wasn't it intuitive for them to see 33/33/33 in their first selection? It's just strange. It's as though most people have no memory of their first selection. The field of statistics involves a lot of conditional probability problems. This problem is an example of that. Example: If I have a bag of 10 marbles, with 5 red and 5 blue, my odds of drawing a red marble change on every selection from the bag and they change depending on what I pulled out, assuming the selected marble stays out of the bag. @@max5250

@@taekwondotimeThe vast majority of 50/50s think probability is limited to 1/# of choices. They almost always understand the 33/33/33 but they can't accept the idea that two doors could have different probabilities.

Agreed. I would say the 1/n thinking is the limit of most peoples' understanding of probability. They learn that shortcut, which usually works, and that's all that sticks. The bigger question for me is why do so many refuse to even consider alternative explanations? Why do they start from such insulting, closed-minded positions?

@@Hank254 "The bigger question for me is why do so many refuse to even consider alternative explanations? Why do they start from such insulting, closed-minded positions?" i'm not shure about it, but i believe, it is a mixture of things: 1)you're pretty shure, you're right and someone else contradicts repeatedly. this is annoying, even if you're not right. 2)no one is happy with being wrong and less happy with being told to be wrong. 3)if a person doesn't want to feel a little shame, it is 'better' to feel anger instead. 4)to many people, not being right is equal to loose 'dignity'. they prefer to claim they're right, even if they know, they're not. in my life, i ran into many people, whose intelligence was very different from mine. there is a tendency, that quite stupid people claim stupid things, loudly and very confident. sometimes, i found myself as well on the side of the louder, confident, more stupid ones. it was for example, when i thought that one of my university math teacher was wrong. i learned, that such persons usually are not wrong and you better think five times before you contradict them...... ...on the other hand: the more intelligent someone is, the more he/she tends to doubt him- or herself.......

@@HollyGraham-wl6ye wrong.

@@HollyGraham-wl6ye ITS 2/3 TO 1/3 YALL THE 3RD CHOICE WASN'T ELIMINATED> U DUBBLE UR TSCHAANSSESS MYSTERY DATING GAME KID LOL THE DREAM DATE BEHIND THE DOOR YO SUCK

@@HollyGraham-wl6ye SPAM SE SPAMMER MAN YO KNOW ITS DUBBLE CHANCE IF YO CHANGE

I thought the host was wanting the contestant to lose the car, thus influencing my answer.

I dont understand this, it makes no sense. if you choose a door and the other is eliminated then the probability should distribute evenly between all of the remaining doors, not all of them except for your choice. Can someone explain why it does this?

@@versenova5531 door 2 and door 3 combined add to a 2/3 probability but you know door 3 isnt it so that 2/3 probability has to be for door 2 thats how i understand it

Exactly, saying that the host will open a door with a goat, before you make your pick, is must for it not to influence your answer in this scenario.

@@versenova5531 you have 33.33...% chance to guess it right, which means you have 66.66...% to choose WRONG. Switching will automatically give you the price 66.66...% of the times. You're more likely to choose wrong, so switching is a better choice 2/3 of the times. That's why it's even more clear with 100 doors, you have 1% chance initially, but after revealing a goat behind 98 doors, it's your best option to switch 99 out of 100 times.

Right, and the random opened door might accidentally reveal the car.

Not really. Because if the car was behind door 1 and you chose door 1, then the host could have opened either of the other doors at random. In that case, switching would have caused you to lose. However, that doesn't change the answer to the question. The question simply stipulated if your chances would be better for you to change doors, not if changing doors would guarantee you the win. And the answer is still yes, that technically, logically, and mathematically, switching, even in that specific circumstance, would have increased your chances of winning. For example, if you look at the example the narrator gives with 100 doors. If you just so happen to pick the door with the car as your first choice, and they eliminated 98 of the remaining doors, that other door still would have a higher chance of being the correct one, except for the fact that you had the dumb luck to happen to pick the one door that wouldn't have helped you.

@@TalkingHands308 The host does nothing randomly, he knows the winning door.

@@TalkingHands308 The host doesn't randomly reveal the car if you picked a goat. That's what they meant. This makes your odds after switching 2/3 instead of 1/2 or 1/3. You will still lose if you switch after originally picking the car.

@@CarMoves you've missed the point of my comment...

"There's a higher probability that the car is behind one of the two doors you didn't pick." Exactly. And also, the fact that host opens the door with a goat, doesn't change better odds of a host in any way.

@@max5250but how is there a higher chance it’s behind a door I didn’t pick

@@GoyMaster You didn't picked 2 doors, not just one. Two doors are twice as likely of having a car behind than a single door.

@@GoyMaster ​Put it simply, there are more wrong doors when you first pick so its more likely you got the wrong door.

@@HollyGraham-wl6ye "ODDS OF THE HOST ? THE HOST- DOES NOT WIN ANYTHING" If player haven't picked the door with a car, can you guess where that door is? If player decide to switch, whose door he will get? "THERE ISNT -- ITS BEHIND THE DOR OR NOT" Yup, it is either behind the door or not, now, if you could only calculate probability..... ROTFL

Its also important to know if you also know this information prior to picking the door.. Because that also changes the probability.

@@bodybuilder6350 i do not think so. Could you explain?

Now i understand what you mean. You are right.

It is important to note that if the host reveals the car, the probability of losing goes up to 100% because the car has been removed from your choices. What this tells us, is that it's a waste of time to think about what the host knows or doesn't know, or what the host's intentions are.

@@alkinooskontopodias5919 if you know or don't know that the host knows or doesn't know. So thats like 2x2= 4 different probabilities depending on what information is known. I am sure you bring in even more play of words and rules that would increase the variables. From the original question we are limited in our knowledge. We didn't even know if he would open the right or wrong door (initially) to expose a car.

only when the information is useful...this is still a 1 in 3 chance for each door. it only helps if the host wants you to win and you trust them to be leading you correctly...otherwise the "additional linformation" is useless.

It really makes no sense… Why does the extra 33.3% (of the 3 options) go to any specific option? Where is the logic for that? If you have for example a coin with 3 sides. But if it lands on the extra side, you reroll (ignore it)… You still have 50% chance of being right. Where does the idea that the extra % goes to the other option than the one you chose at the start come from?

@@heihvyegs It makes total sense. probability can be calculated by enumerating all possible scenarios. Write them down for the three doors and see what you get.

@@tjmozdzen I’ll write them down later. But… You can eliminate everything before the final option “Do you change from A to B?” Because you will always end up at that same point…?

@@heihvyegsThe logic cant be found easily in a 3 door example. There probably you will have to do the experiment 100 times to get an advantage. The real benefit is shown in the 100 doors example. Imagine you run the test of 100 doors 100 times and you stick to your original choice each time. You will win once. But if you change all the time, you will win more than once. Cause more doors means more information. In 3 doors the information gain of revealing a door is the minimum and difficult to perceive. You just have to magnify the problem to get "faster" wins. It is the same with the stock market. Big companies have billions to invest and manpower to do it multiple times ino order to get that 0,0000001% profit which is mathematically guaranteed and real big if your assets are in 100s of billions. You will never bother to spend 6 months of your life to win 1 dollar out of 10K, though, just by yourself. The latter has generated a perception that its impossible to get a "vector" in randomness. But normal distribution is the first proof that randomness indeed can have vector to show you direction.

At least they did realize that the math checks out in the end and that the initial doors do matter, not a 50-50. "Yes, it makes sense to switch" "As the number of doors that the game starts with declines, the odds of you winning by switching diminish" Sadly once they realized that they turned to insults instead, but they do understand the idea behind the problem now.

@@Jurting His latest post says with 3 doors it is 50/50. He is just trolling.

Fool, the chart and trying to use a 100-door game to prove the 3-door game is bogus. In the 3-door case shown in the video, it makes NO difference if you switch in THIS case where door 3 is opened. I'm sure you're too immature to do as follows, and just with to hurl childish insults. When you grow up, do the following: Make a drawing as described below. There are 3 outcomes for the game (car is behind door 1, 2, or 3), so: Draw row 1 with 3 doors. Write "car" on door 1. Door 2 is blank. Draw a large circle on door 3 to show that it's been opened. This is case/game 1. Draw row 2 with 3 doors. Write "car" on door 2. Door 1 is blank. Draw a large circle on door 3 to show that it's been opened. This is case/game 2. Draw row 3 with 3 doors. Write "car" on door 3. Door 1 is blank. Draw a large circle on door 2 to show that it's been opened. This is case/game 3. Now, according to the rules stated, the host will always open a door with a goat. So in case 1 (shown in row 1), if you switch you lose. In case 2 (row 2), if you switch you win. In case 3 (row 3), if you switch you win. So, you win by switching in 2 out of 3 cases (case 2 and 3). Since it makes sense to switch in 2 out of 3 cases, you now think "It pays to switch". HOWEVER, in the case in the video, you selected door 1 and door THREE is opened, NOT door 2. Therefore the last row in the drawing does NOT apply since it shows door 2 being opened. Therefore, the case in the video is either game 1 or 2 (represented by rows 1 and 2). There are only 2 possibilities for outcomes now. Either you switch and you lose shown in row 1, or switch and you win shown in row 2. So it makes no difference if you switch or not. Now let's say that door 2 was opened instead of door 3. Strike row 2 then (instead of row 3), because it's either scenario 1 or 3 that applies. Again, in one case it pays to switch, and in the other it doesn't. In the 100 door example your odds of winning increase greatly if you switch doors. It's pretty obvious. As the number of doors that the game begins with declines, the odds of you winning by switching diminish, and by the time it's down to 3 doors, the odds of winning by switching are down to 50/50, at which point it no longer matters if you switch or not.

@@joevarga1769 Nice wall of text. Sadly, 2 is still larger than 1 even if you wish it wasn't because you answered the question incorrectly initially because it's counterintuitive. Time to stop trolling and just admit that your intuition failed you in a solved probability problem that is famous *specifically* for being counter-intuitive, It's no big deal.

@@Jurting Copy and paste the part where I answered the question incorrectly initially. Copy and paste the part where I admitted that I was wrong.

If he doesn't behave randomly, the it ain't a probability question. It's more along the lines of 'form' like at the horse races . We then talk more about odds . No strict rigourous standard calculations for odds . It something settled on by experts . However the probability calculations are ½ for a choosing from two given options for which absolute randomised conditions apply.

@@philip5940 you're confused. It is a probability question, but the difference is it's about posterior versus prior probabilities. just write down all possible options; pick one at random, and consider all of the different ways that the prize might be distributed. Count what happens when you switch or stay. you have 1/3 chances of getting it right by guessing out of the box. He then shows you one of the places the prize ISN'T (that's the part that's not random). Now you have 2/3 chances of winning if you switch. Why? Because there was 2/3 of a chance at the beginning that it was in one of the spots you DIDN'T pick, and he showed you one of the places where it isn't, so those odds still apply; you have 2/3 chances of getting the prize if you switch. It's a classic problem that is now commonly taught in probability, known as the Monte Hall problem (he was the host of the game show). If you don't believe me, write down 3 doors, put the prize behind one of the (doesn't matter which), let's say it's behind door 1. Now say you pick door #1, and it's behind door #1. He shows you either 2 or 3 (where there's a goat), if you switch you lose. Say you originally pick door 2. He has to show you door 3, where there's a goat, if you switch, (to door 1) you win. Let's say you pick door #3; he has to show you the goat behind door 2, you switch, you win. Count it up; 2/3 chance of winning if you switch. It's also ironic you're arguing about his given that the entire point of this video is to explain to you how your answer is wrong.

@@bartonanderson1106 seems that the entire point of the video is to show the power of spin and to highlight mass gullibility . ⅓ and ⅔ probability when given three choices are now a phantom that have ceased to exist The new state is two choices for which the probability is 50/50 .

@@philip5940 I just explained the entire logic to you; you're obviously not capable of understanding this, but here's another chance: en.wikipedia.org/wiki/Monty_Hall_problem

@@philip5940 Since the host always removes a goat that is not which the player picked and neither which contains the car, then that means that the other he leaves closed is the winner one as long as the player starts failing, and that occurs 2 out of 3 times on average, not 1 out of 2. This is better seen in the long run: imagine you played 900 times. In the first selection you are equally likely to select the option that has each content, so in about 300 times you would get which has goat1, in 300 which has goat2, and in 300 which has the car. In total, 600 times a goat and 300 times the car. As the host will reveal a goat from the two doors that you did not pick in all the 900 games, in the 600 that you already have a goat, the revealed goat must be the second one, and so the car is in the switching door. Only in the 300 games that you had the car behind yours, the switching door will have a goat. So, always two doors left, but yours results to be correct 300 times, and the other that the host leaves, 600 times.

Oh that makes sense

Thank you, I saw this explained on another video, I don’t understand why mathematics people are disagreeing with this simple fact of probability, it’s not that hard to understand

I still don't agree with this no matter if its correct because 1 out of 3 is not 1 out of trillion or 100 or 10 its still out of 3 so it's completely different.

@Krichnu It is the same; that's the point. It doesn't matter if you agree, because the math checks out. Find the comment on this video where the guy wrote a program and ran this simulation 10,000 times with 3 doors (or whatever the number was).

Can you imagine how you would feel if you switched and were wrong? @@MrMcSnuffyFluffy

Huh?

@@HollyGraham-wl6ye huh?

Because the host is not playing the game, he is presenting the game. He is not trying to keep the car. Huh?

We Russians knew of several men and women with IQs higher than 235 to 239 and you boast about her? If I were you I keep them as a group of natural security assets. But one of them, a woman said this, IQ IS NOT EVERYTHING! You may have a higher IQ but still remain a complete utter boop if you did not receive the required proper education to make use of it. In fact, she says, proper educational environments can practically increase the IQ of EVERYBODY, man, womand, and child if we are willing to have the political will to do it!

They did it on Mythbusters. Switching works.

@@archwaldo Anyone who can write macros is a mythbuster here xD

It's not hard to understand the pyramids !! By vibrating within the earth's "B" field they could communicate as well as travel intergalactically. My goal is to educate others. Just for clarification. The center of a magnet is by far the most powerful. AC current Radio frequency signals could not travel without the "B" field. The oscilloscope never shows the "B" field but it is there. otherwise it would show a short circuit as the two polarities collide. The "B" field pushes everything forward. Things you can do to see the "B" field:1> vibrate the "B" field of a magnet near a trickle of water and watch the water repel the same.2> Vibrate the "B" field on plastic or glass and watch the item lose weight!! You must understand, don't try this on iron or metal; it will distort the magnetic field . 3> Vibrate on Granite rock and it will become weak. and You can cut and shape ONLY with copper tools. AGAIN pay attention to the magnetic field you can't use iron tools for this action. . 4> I have not proven this part yet, but you should be able at the correct Two frequencies to levitate non metallic objects. FYI I think that's why most UFO's don't show on radar they are not metallic. I have come to believe we are all operating on the magnetic "B" field. The entire universe is 100% magnetic, we are an algorithm of the same. Think about this : The pyramids were communication and transportation device's of yesteryear: When you install such a huge mass within the "B" field of earth they intercommunicate via the "B" field. FYI I have teaching credentials and much much more. Want some Proof, Check out Coral Castle in Florida on RU-vid, all his generators were set up in the repel mode to maximize the "B" field into the earth FACT!! The stones at Stonehenge and KT were part of the "B" field system, The stones would vibrate at frequencies that would stimulate the crops and many other things. Those were the true power plants of yesteryear. WB6HUN/1958

Well worded. Regards!

If you like goats and cars, you can't really lose.

I guess I still don't get it. "The host always chooses the other goat, that means 2/3 of the time the car will be in the other door." I ask why? Why wouldn't the probability shift to say the car will be in the door you originally picked 2/3 of the time and therefore don't switch your choice of door.

@@waakca The host must always reveal a goat, but it must be from the doors that you did not pick. That's the rule of the game. It means that whenever you start selecting a goat, the revealed goat will necessarily be the second one, so the car will necessarily be in the switching door. And you had 2/3 chance to start selecting a goat. Only in the 1/3 cases when you start selecting the car, the other door that the host leaves closed will have a goat.

​@@RonaldABGwtf are you trying to say?

you know paul erdos? he was one of the most dominant mathematicians of the 20th century, and he was an expert of stochastics. he didn't want to believe the outcome and struggled to understand what happens. but it was not because the problem is difficult to understand, it was because this problem is deceitful.

this actually does it for me, at first i thought monty hall problem is only logical to switch when you have more than 3 doors

@@tactic2569 well if the total num of doors is 3 + x, with x being more doors added. If monty hall removes 1+x amount of goat doors, Then the chance of winning is 2+x/3+x and losing is 1/3+x. Meaning it would be even more logical to switch if more doors are added and monty removes more goat doors.

It still makes absolutely no sense to me. There are two doors after you remove the 1.. q of the two doors has the prize.. I don't get it lol

I got it a different way-- in the 100 door example, you pick a door randomly, then 98 wrong doors are removed. Your door can't be touched, but the right door also can't be touched. Your door was originally chosen at random, so switching doors would be better, since you have more information to make the choice with. Although this method probably wouldn't work for any other problem and I just didn't know any other way to rationalize it.. Here's an extra thing: I also thought, "hey, the probabilities just merged into one door! That's cool." Without really understanding why it happened.. :/

@@joeyeddy9344 even if probability of something is 99%, it's still possible that 1% is the final answer.

Yep. Yet, this sound like differential calculus to some people on RU-vid.

it's quite simple for all those, who aren't trapped in this "one out of two-->fifty fifty" illusion.

​@KarlHeinzSpock it's 50/50.

@@EthanFaidley you're the next victim of the illusion. take note of the fact, that this simple problem has been solved decades ago and the solution passed the review of several generations of mathematicians.

@@EthanFaidley "it's 50/50." It both doors would hold a car with 50% chance, that would also mean player can pick the winning door from 3 closed doors, with exactly the same success rate as a host, who get's twice as many doors, and knows where the car is.

@@EthanFaidley Assume you stay with your first pick. If your first pick is Goat A, you get Goat A. If your first pick is Goat B, you get Goat B. If your first pick is the car, you get the car. You only win 1 out of 3 games if you stay with your first pick. Switching means the opposite. It's just basic math/logic kids understand. Sadly, it's far too hard for idiots.

I'm not a genius, but when I was presented this problem, I saw it right away because I only thought about switching to the winning side. I realized that removing a goat does not effect the chance of having the car.

Why would you change your choice to BOTH other doors if one of the doors has been already disclosed? The choice can be either to keep your FIRST choice or opt for the SECOND door. You are left with 2 doors and you don’t know behind which door is the car? The odds are the same. Easy peasy.

@@mr.jollybear5180Switching to the other side is, in a way, getting both doors because if the car WAS on the host's side when he had 2 doors, then it's guaranteed to be on his side when he has only 1 door left. In other words, it's easier for the host to land the car on his side, and once it's landed on his side, he cannot get rid of it. Therefore you should switch to the side that has more room for the car to land.

@@mr.jollybear5180 think of this differently. Imaging that at the beginning you are given the choice: door A or both door B and C - if the prize is behind door A and you choose door A, you win; on the other hand, if you choose both door B and C, if the prize is behind either, you win. What would you choose? Of course, door B and C. Why? Obviously, you win 2/3 times. Now imagine. You choose door B and C and then the emcee shows you what's behind door B and it's a goat. Should you switch to door A or keep door C? The thing to bear in mind is that disclosing information doesn't change the probabilities. For example, if the emcee shows you that behind door B is a goat, that didn't change the probabilities associated with choosing both door B and C - switching means going from a 2/3 chance of winning to a 1/3 chance.

What if you do not picked one?

@@1984Kojot picking one is equivalent to not switching after the host opens a door

disagree. You flip a coin, neglecting the edge probability, you have either tails or heads. When you flip you always have 50% chance probability of landing either heads or tails. However, flipping 50 heads in a row is extremely unlikely and thus getting a 51st head in a row is, too, extremely unlikely, despite having only 2 outcomes. Lavant's high IQ is garbage and false or she cheated on her test. IQ test measures several things: verbal, reasoning, memory, processing speed. Yes, those 4 combine into 1 IQ score, still, I would love to see her true published IQ test. Until then I call bullshit.

@@vkaa3k190 Chance for any of the doors to have a car is 1/3. Then the host is opening one door. But host is not allowed to open your door -> your door is a separate group of propabilities -> the door that is revealed transfer its probability to the other door in its separate group... Or You make decision to stick with your initail choice(when all 3 doors were unknown) = you are ignoring that extra information provided to you by the host so your chances do not change...

@@vkaa3k190Mate, this problem has been resolved by mathematicians, not just Vos Savant, since the 90s... you're making a right fool of yourself here.

@@fleurdemaiko lots of mathematicians have called out her bs, so you are the one making a n**ger out of yourself. And you don't have to have a PhD in math to figure out the probabilities.

I am so happy about it too. I knew that you could easily write it out but the idea to do it with 100 doors blew my mind. Then without writing it out, it will make more sense to many people.

Probability is a coin does it fall heads or tails?? and may be one in two thousand flips it lands on its edge ?? play roulette on red or green?? sit and wait for a run of 7 red?? then bet on green? logic says it as a good chance of falling on a red??? Yet really every time is a new happening and as a chance of red or green or may be the bankers zero's You just got to feel lucky

It's not an explanation. It's a false spin .

The speed of Light is a very insignificant item. Has little to do with the universe we live in. The pyramids were used for not only instantaneous communications but also for instantaneous physical transportation to other galaxy's. E=MC2 has absolutely no relevance to anything!! Wake up please!! We live in a 100%magnetic universe! The center of a magnet will show you anti gravity, It also will show you how to repel water, we will no longer have a problem going to extreme depths. Do some basic experimentation using the center of a magnet it will blow your mind. However, Keep in mind the magnetic field you cannot use any iron anywhere near, it would disrupt the center field of the magnet. As you know I refer to the center of a magnetic force the "B" field. You can tap glass plastic anything other then iron and it will loose weight. That is exactly why they used copper tools to build the Pyramid's Please review "CORAL CASTLE Florida on RU-vid> What he did was transmit the "B"field into the ground via his generator that was set up with 25 "V" magnets five deep, all in the repel mode to maximize the "B"field energy about his property and he also had a horizontal stone similar to Stone Henge on his property. Don't waste your time on E=mc2 it has no relevance to anything!! If you take a granite rock just like those used on the pyramids and "VIBRATE the "B" field into same at the correct frequency it will become easy to cut with a copper tool. FACT!!!! Please get the tools you need to learn the facts.!! Thanks

The Monty Hall problem is flawed. The question poses two completely different scenarios 1 being "If you choose a door #1 and the Host opens 'another door'" ...then it proceeds to add information thus changing the question..."If you choose door #` and then opens the third door" So there's nothing mystical or profound about this quesiton, it's simply flawed. Yes the player might have an advantage with the first scenario as seen by Marylin's Graph, but the Second question, once that third door is opened the problem negates the graph because she's showing the third door not beign opened as a variable xD

A fool takes no pleasure in understanding, but only in expressing his opinion. Proverbs 18:2

Have the person trying to understand the problem play the role of Monty Hall using playing cards or something with someone who will always switch. They should soon realize that Monty Hall will have the car 2/3 of the time.

Host is not allowed to interact with door that was initialy selected that is why its chance for having a car do not change. So you ending with tree doors one with 1/3 chance(the one selected when no information about one of the doors was known), one with zero chance as the host is allowed to open only the door whithout car and the third door takes the whole propability of the group of doors that host is allowed to interact with => 2/3.

I find that people have a heck of a time realizing that (if one picks and sticks), actions after that decision make no difference whatsoever as to the outcome If monte does nothing, she will win 33% of the games If MONTE opens a goat door, she will win 33% of the games. And if Monte would even open a car door (when one is there) she would win 33% of the games. Also, I think some of these do not realize the simple concept that if we know "she will win 33% of the games", that means that in any one game the chances of winning by sticking is "33%"

When you pick the first time you have a 1 in 3 chance of winning. But what really happened is that 1 door got removed and you was ask to pick a second time your odds no matter the door and with no other info became 1 in 2 chance's of winning no matter if you picked the same door or changed doors.

@@RipMinner no, door with a goat got removed. The door you chose still have 1/3 chance of having the car same as before.

Yea, basically, you want to choose a goat first , then you're guaranteed to win by switching. Since THERE'S a 2/3 chance of picking goat, you got a 2/3 chance of winning. The only way to lose is to pick the car first, only 1/3 chance.

@@hmm1778 Because 2=3?

@@hmm1778 no...your chances are 1/2 now. Consider the 3rd door was never there. What now?

Or out of three shots you wouldn't put the goat side by side, also understanding how the conditioned brain works.

Unfortunately it's not clear how it's not 50%. Even if I picked the right door the first time (say door 2), the host would have picked the wrong door (say door 3) and offered me door 1 or 2. The same applies if I'd picked door 1. So to me I don't see how the hosts actions increases the probability of the unpicked door having the car.

@@nitinullas it's not 50% because there is a much deeper intelligence at work, you have the social norm mathematical equation that would give door one the better chance. 😉 and then you have the social norm that only sees what's right in front of them. Think deeper or overthinking makes for a much wider probability of intelligence. Hint: shallow thinkers of black and white only see 50% chance.

@@nitinullas It is quite clear. 1/3 times you pick the car. This means your odds of winning by staying are 1/3. By staying you only win when you initially chose the car. 2/3 times you pick the goat. This means your odds of winning by switching are 2/3. By switching you win by initially choosing a goat and switching to a car.

@@nitinullas Well, the probability does not change. That is part of the reason. And the host itself is not free to do what he wants - he is restricted in his actions as he is only allowed to open a door with a goat. If he would open doors freely and the doors would contain like envelopes with a key or a "you lost" note the probability would not change. Think about it this way. Your chance to pick the correct door is one out of three. In this case the chance that the car is behind one of the other two doors is two out of three. This does not change when the host opens a door. The chance you chose the correct door is still one out of three and the chance that the car is behind one of the other two doors is still two out of three BUT the host opened a door with a goat as he is not allowed to open the door with the car. Therefore the chance that the door you did not chose contains the car is two out of three. The point is. You chose door A. Car can be behind A or B or C. If it is behind A the host can either open door B or C. If you switch, you lose. If the car is behind door B the host can ONLY open door C. If you switch to B you win. If the car is behind door C the host can ONLY open door B. If you switch to C you win. Even in this small example you can already see that you win in two of the three cases if you switch.

Correct.

She is correct about the 100 doors, but wrong about the 3 doors. With the 3 doors and one being eliminated, your chance between the 2 last doors is actually 50%. Her theory of switching doors is only practical when there are more than 2 doors remaining. To test this I generated a computer program with the scenario set up, I recorded by hits and misses of 'would you like to switch?' with the 3 doors (2 remaining) and it worked out to be 50% over 1000 attempts. Incidentally, the choosing to switch only had an effect when you started out with more than 3 doors.

@@seascs You are wrong. Switching improves your odd. Think of it this way, if the host does not reveal the goat, and offers you both door 2 and 3, would you switch? Of course you would because you have 2 chances of getting the car. Revealing the goat doesn't change anything because he can ALWAYS show you the goat! (it's an illusion, he actually does nothing)

@seascs this was exactly how I assumed it would go. You should post the experiment somewhere. With more than 3 doors the edge is obvious. But with only 3, and 1 free elimination its back to a coin flip. Everyone seems so damned convinced of the answer that Im wondering how we can actually run the experiment.

I cannot believe it.

@@cvn6555 Why can't you believe it?

What about intention in this equation. The people at Let's Make A Deal know where the winning door is, so their intention could be to help or to harm. Is that not a variable.

@@joewhite4170 Yes, that is why they only open a door that does NOT have a car behind it when they open one of the doors. ;-)

I just laid it out like at 3:24. It took 2 minutes, and made it apparent why it's better to switch in a concrete and intuitive way.

Seemed to me "they" were sort of picking on her for not using the "math stats" as they did ? Oh, of course; now let's hear it for the "Intelligence of Creative Thinking!?" It seems THERE ARE different "kinds" and "types" of IQ " Tests." Experience and Education , two possibly different types ? So we should be also asking WHICH IQ Test did Marilyn excel in, or on ? MISSING FROM the video; Does this lady write and speak in both German and Italian ?I've always felt there is an extreme indication of high intellect in regard to peoples' abilities TO express themselves in foreign languages ?Seems there is a certain "type" or "kind" of logic it seems in learning to "relate " foreign language to one's own ability to speak and write in their native language ? It appears Marilyn 's " (by assumption?) that Marilyn had TWO "Native languages" yes ? Her opinion of "public schooling" holds great merit. I remember a question required to be asked on a high school test , was "Who were the Phoenicians ?" The ABCD Answers included the answer " Venetian" . Most admitted later that they all misunderstood the word Phoenicians because they were all more "familiar" with Venetian Blinds, than historical terms of peoples and places! (Ha Welcome to American World History 101-we (all) need to repeat that one!?) Which btw lead to my last question (for you or Marilyn, ha ?) Is the inability to "spell" properly (in any language/especially ones native language ) indicate ignorance ?Duh...As a retired teacher, I submit I've become dependent on the Google Gargoyles ' offers for correction, which often just doesn't exist. The robots tell me I've misspelled something, yet/while, offering no options with which TO correct it. Good at Questions; Slow at the answers. Anyone ? "I Ain't no Middleman" Fred Gold & Lynda Faye Copyrighted 2016 by LyndaFayeSmusic@gmail.com or Yahoo, if censored for using the word " God" too often?

You are not wrong. They are wrong because they explain the problem as if it's not Monty Hall. Monty Hall requires the host to reveal a goat. That reduces the possibilities from 6 to 4. Switching from one door to another doesn't increase the chance to getting a car. Both door has equal chances.

Are you married? You will find that you are wrong a lot more.

I'll try to explain it to you: Basically, imagine there were 100 doors, and one of them holds a car, the rest 99 hold a goat. Now, you get to choose one door in the beginning. Then, the host eliminates 98 of the wrong choices. There is now one other door left, along with your first choice. Should you switch, or should you keep? Obviously, you should switch. Why? Because, when you first chose a door, you had a 1% chance(1/100) of it being a car. Now, you get to pick between two doors. Therefore, the second one will have a 50% chance of holding a car. Its the same logic with 3 doors as well, increasing the scale helps understand it. Hope this helped:)

@@dreamon8274 The remaining door has 99% chance, not 50%

think about that: when you've chosen a door, the host doesn't open a door, but he asks you, whether you want to change and take BOTH other doors. you agree and open them. then you remove one goat, as the host would have done it for you in the original setting

It is simple: the host offers to you the two other doors in exchange for your door. Betting on two doors doubles your chance to win. The only reason why you only pick one is because one is already open and a goat. What isn't so obvious: the host is offering to you the rest of your first choice, but that is what he actually does.

@@dreamon8274 Thanks for the detailed explanation which I’ve read over and over. For some reason I just can’t grasp it. It’s annoyed me for years. Hopefully one day it’ll sink in.

You got it

Great. Now note that if you select door #1, switching offers no advantage at all unless the host opens door #2 and there's a goat behind it. Then, if you don't switch, you lose. Do you understand why this is?

@@klocke5247 Still desperately sticking to one out of 3 equally probable states?! Poor K Lockeless...

@@klocke5247 In the case of 3 doors, it gives you a very slight advantage if you switch. If you look at the scenarios in this image (3:20) The top three show that you would win 2 out of 3 times if you switch. The bottom three show that you would lose 2 out of 3 times if you stay. In the case of 100 doors, your odds are 99/100 if you switch. For 3 doors, it's 66.6/100 if you switch. It seems like it shouldn't be that high of a probability with 3 doors. I guess 66.6/33.3 is a lot closer to 50/50. I wouldn't be as confident switching with just 3 doors.

@@BillGraper thank you Bill

But the clicks! We must write the clickbait for the clicks!!!

This comment is gold.

@1978ajax No she achieved the Mensa 228 IQ test in a supervised manner (they are always monitored tests). However, she spent a lot of time actually studying IQ tests and sitting them privately which makes you much more versed in the problems and questioning style and can help achieve much higher scores, than just being thrown an IQ test out of the blue as most people are when tested at school etc. You must still read and comprehend the questions however, as they may slip in updates / variance or even completely new problems. She almost certainly has a photographic / Eidetic memory and can memorize anything. She writes and publishes books. So for all the massive IQ she has, she hasn't really invented a space warp drive or anything, which a lot of people perhaps expect. That's not how people's intelligence and lives work really.

@1978ajax She's in my Psych text from over 22 years ago... her maiden name was Marilyn Mach ( descended from Ernst Mach, the Physicist ).

yes same as people knew that earth is center of universe. :D ..... To avoid being burned at the stake, the 69-year-old was forced to renounce his belief in a heliocentric model of the universe. And so I see you, Trying to burn those with different oppinion :)

But only knew this from 21 and annoying friends pretending they can explain it. I can’t recall if 21 presents it this way