Fluid pressure integral problem. Pretty easy, although I'm getting wrong answer

MathGangsta

1. The problem statement, all variables and given/known data

http://books.google.com/books?id=hMw...merged&f=false

It's number 11 on that linked page.


2. Relevant equations

F = w int y*f(y) dy

3. The attempt at a solution

I used 2-y for my height and y^3 for my width, I then multiplied by 2 for symmetry on the width. I then integrate from 0 to 2. I keep getting the answer: 16/5w but the book says it's 64/5w. I'm just not seeing it. I'm positive I have the integral setup correctly. I've checked it numerous times. Thanks for any help.