Well, the formula for the volume of a cylinder is V=πr²h so you would have to plug the numbers in next. The radius would be 6, because the diameter is 12. When you plug all of the numbers in, the equation would be V= 3.14×6²×4. Then you solve.
V= 3.14×36×4
V= 113.04×4
V= 452.16
The volume of the cylinder is 452.16 ft³.