Gravel is being dumped from a conveyor belt at a rate of 25ft3 per minute. It forms a pile in the shape of a right circular cone whose base diameter and height are always equal. How fast is the height of the pile increasing when the pile is 18 feet high? Submit an exact answer in terms of π. Hint: the volume of a right circular cone with height h and base radius r is given by V=13πr2h.