Thank you, everything makes sense now.
Ok so when I evaluate my Volume I get a really huge number 3000 something which I know isn't right. This is what I evaluate. 2pi* the integral from 0 to 5.5 of ((-21)/2(5.5)^2pi (x^2)+ 21/2pi))^2dx. When I put that in my calculator and integrate I get a huge number. A friend of mine suggested I try a quad regression but I don't know how to do that on the calculator. Please tell me what I did wrong.
I did show you my steps. ok I get for the equation Y = (21/2pi) - (21/2pi(5.5)^2) x^2. and then when I put that into the Volume formula I just move 2pi out front and square f(x) I put the whole function into my calculator and I use my calulator to integrate from 0 to 5.5 I get 3000 something
$\displaystyle \displaystyle 2\pi\int_{0}^{5.5}\left(\frac{21}{2\pi}-\frac{21}{2\pi *5.5^2}*x^2\right)dx=21\left[x]^{5.5}_0-\frac{21}{5.5^2}\left[\frac{x^3}{3}\right] _0^{5.5}$
$\displaystyle \displaystyle = 21*5.5-\frac{21}{5.5^2}\left[\frac{5.5^3}{3}\right]=77$