ok, i drew out a diagram and I have no idea how or where to start this problem. Please help guide me so I can learn how to do it...

A water tank has the shape of an inverted circular cone with a diameter of 4 feet and a height of 6 feet. If the tank is full, find the work required to empty the tank through a pipe that extends 3 feet above the top of the tank. Use 62.5 as the weight-density of water. Give your answer in foot-pounds.

(Doh)