1. The problem statement, all variables and given/known data A 54.0kg cheerleader uses an oil-filled hydraulic lift to hold four 120kg football players at a height of 1.30m . If her piston is 19.0cm in diameter, what is the diameter of the football players' piston? 2. Relevant equations I think the only equation needed is (F1/A1)=(F2/A2). I didn't think that density or the height being raised was relevant in this problem 3. The attempt at a solution So first I rearranged the formula so that ((F2A1)/F1)= A2. I know that the force is the weight of the cheerleaders(54 kg) and the four football players( 480). The value g cancels out, so I'm left with .... (480pi(r1)^2)/54= pi(r2)^2 so by subbing in for r1 ( .095m) I get... .252=pi(r2)^2 I then rearrange the formula to solve for r2 r2=sqrt(.252/pi)=r1=.283 then to get the diameter I multiply by two to get .566m or 56.6 cm This however, is not the right answer. Can somebody please help?