If you have the volume of a cylinder 128(pi)in^3, the height of 8, and X as the diameter, what's X?
128pi = pi * radius^2 * height
128 pi = pi * radius^2 * 8 divide both sides by 8pi
128pi / [ 8 pi ] = radius^2
128/8 = radius^2
16 = radius^2 take the square root of both sides
4 = radius........so.....the diameter = twice this = 8