Gravel is being dumped from a conveyor belt at a rate of 20 cubic feet per minute. It forms a pile in the shape of a right circular cone whose base diameter and height are always the same. How fast is the height of the pile increasing when the pile is 22 feet high?

h=22

r=11

r=1/2h

V=1/12*pi*h^3

dv/dt=1/12*pi*h^2*dh/dt

dv/dt=1/12*22^2*pi*dh/dt

dv/dt=40.33pi*dh/dt

where do i go from here?