How does it do thank you very much?

Question

Gravel is being dumped from a conveyor belt at a rate of 40 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 24 feet high? Recall that the volume of a right circular cone with height h and radius of the base r is given by V = [1/3]πr2h.

Answer 1

Something is wrong. If the base diameter and the height are always the same, the cone has always the same volume. If you're adding material, where it goes?
I think you've missed something. Could it be that the ratio between the base diameter and the height is always the same?

Answer 2

V = [1/3]πr2h
r = h/2
V = (π/12)h^3
dV/dt = (dV/dh)(dh/dt)
dh/dt = (dV/dt)/(dV/dh)
dV/dh = (π/4)h^2
dh/dt = (40 ft^3/min)/((π/4)(24 ft)^2)
dh/dt = (20 ft^3/min)/((3π ft)^2)
dh/dt ≈ 2.122066 ft/min ≈ 2.1 ft/min