please explain

A 2 hp motor can do 1100 ft-lbs of work per second. The motor is used to pump the water out of a swimming pool is in the shape of a rectangular parallelepiped 8 it deep, 48 ft long, and 19 ft wide. How long does it take for the pump to empty the pool if the pool is filled to a depth of 7 ft? The weight of water per cube foot is pg = 62.43 1b/ft?. (Use decimal notation. Round your answer to a whole number.)