Answer:
6075π ft^3 
Explanation:
The formula for a cylinder is πr^2 * h
were: 
h = height 
and r = radius 
and because the radius is always 1/2 of the diameter, the radius is 22.5.
So now we plug everything in: 
π*22.5^2 * 12 
= π*506.25 * 12 = 
π * 6075 = 
6075π
please don't forget to add the units.