Sand Is Pouring from a Pipe at the Rate of 12

Multiple Choice

Sand is pouring from a pipe at the rate of 12 cubic feet per second. If the falling sand forms a conical pile so that its height is always the diameter of the base, how fast is the height of the pile increasing when the height of the pile is 6 feet tall? Round answer to nearest hundredth.

A) 0.21 ft/sec
B) 0.07 ft/sec
C) 0.25 ft/sec
D) 0.03 ft/sec