Gravel is being dumped from a conveyor belt at a rate of 50 cubic feet 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 22 feet high?

The height of the pile is increasing by ftmin\displaystyle \frac{\text{ft}}{\text{min}} (round your answer to 3 decimal places)