Uh I have a doubt in the last question. From part b onwards, why did you use the cross multiplication method instead of using the formula f = fd/w. Wouldn't using that be the appropriate method, as we're trying to find the frequency?
Yes the axis goes up in 2's, but if you look closely on the graph, the bar goes halfway between 2 of the lines, so it has a height of 8.3 which is multiplied by the width of 10 to get 83cm^2
Side note: When using a calculator, convert the lower value also using the standard coding method, eg: usually lower bound is zero, but in this question (0-50)/4=-13.25
