Volume of a circular cylinder

Question

The volume of a circular cylinder varies jointly as its height and the square of its radius. If a cylinder with r=2 feet and h=4 feet holds 50.24 cubic feet of water, what is the volume of water in the cylinder when h=3 feet?

Answer 1

Only the height changed.

Therefore the volume changes as the ratio of heights, 3/4

(3/4)(50.24)the 

 37.68