Originally Posted by

**Soroban** Hello, jasonlewiz!

Theat"vertical plane" decription is confusing.

If I read it correctly, it means that the circular ends of the cylinder

. . are perpendicular to the axis of the cylinder.

That is, we have a *right* circular cylinder (which happens to be tipped).

We have an outer cylinder with radius 6 and height 3000.

. . Its volume is: .$\displaystyle \pi (6^2)(3000 \:=\:108,000\pi\text{ ft}^3.$

We have an inner cylinder with radius 5 and height 3000.

. . Its volume if: .$\displaystyle \pi(5^2)(3000) \:=\:75,000\pi\text{ ft}^3.$

Therefore, the volume of the concrete is: .$\displaystyle 108,000\pi - 75,000\pi \;=\; 33,000\pi\text{ ft}^3.$