The volume of a cone varies jointly as the square of its radius and its height. If the volume of a cone is 25π cubic inches when the radius is 5 inches and the height is 3 inches, find the volume of a cone when the radius is 3 inches and the height is 6 inches

Answer 1

v = k r^2 h
That is, v/(r^2 h) is constant
So, you want v such that
v/(3^2 * 6) = 25π/(5^2 * 3)

or, knowing as you do that
v = π/3 r^2 h
just plug in your numbers directly