The volume of the pipe is about 282.6 cubic feet.
First, we need to find the area of each circular cross section and subtract them to find the width of the pipe. The area of a circle is pi(r^2).
pi(3^2) - pi(2^2)
28.26 - 12.56 = 15.7
The width of the pipe is 15.7. Now, multiply that by 18 to find the volume.
15.7 x 18 = 282.6
