1.  Falling Sand Sand is falling off a conveyer and is forming a conical pile at the rate of 20 cubic feet per minute. The diameter of the base of the cone is approximately three times the height of the cone. At what rate is the height of the pile changing when the pile is 10 feet high?

2.  Water Tank A conical tank (with vertex down) is 10 feet across the top and 12 feet deep. Water is flowing into the tank at a rate of 10 cubic feet per minute. Find the rate of change of the water depth when the depth is 8 feet.