Thank you so much for illuminating how to do combined rate problems! I found these so confusing, but now I think I have a solid understanding and systematic approach. Thank you.
Hi Jeff, How would I use the formula you've mentioned with this problem? Working together, 7 identical pumps can empty a pool in 6 hours. How many hours will it take 4 pumps to empty the same pool?
Hello Jeff, How can we apply the same above formula for the 700 + problem below, Lindsay can paint 1/x of a certain room in 20 minutes.what fraction of the same room can Joseph paint in 20 mins. if the two of them can paint the room in an hour, working together at their respective rates?
lindsays rate=1/x by 1/3=3/x.rate of joseph can be calculated with the above formula to be 3/(3-x).now since we are asked for 20 min it would be 1/3-x. plz let me know if its right or wrong
Let assume x any value say 6 G paints 1/6 of room =20min G paints 1 room =120min G+J=60 min(last line) Taking LCM of both We get efficiency of B=1 To get fraction of room painted by J;take ratio.i.e.20/120=1/6.. Use options and use x as 6. If any option equals 1/6 that will be the answer.. Hope it will help you.
Let 1/x be the fraction of the room that Lindsay can paint in 20 minutes. Let 1/y be the fraction of the room that Joseph can paint in 20 minutes. Lindsay's Rate= 1/(20x) rooms per minute Joseph's Rate= 1/(20y) rooms per minute Then from the Generic Equation we can write: 60/(20x) + 60/(20y) = 1 3/x + 3/y = 1 solving for 1/y we get 1/y= 1/3 - 1/x=(x-3)/(3x)
