Suppose that we pump water into an inverted right circular conical tank at the rate of 2 cubic feet per minute (i.e., the tank stands with its point facing downward). The tank has a height of 14 ft and the radius on top is 4 ft. What is the rate at which the water level is changing when the water is 7 ft deep? (Note that the volume of a right circular cone of radius r and height is h is V=1/3pir^2h.