A pump can fill a tank with a water in 2 hours. Because of a leak, it took 6 hours to fill the tank. The leak can drain all the water of the full tank in how many hours?	Choose one: A) 2 B) 3 C) 4 D) 5 E) 6
The rate of the pump + leak = 1/6   1/2 - leak's rate = 1/6   leak's rate = 1/2 - 1/6 = 1/3   The leak will empty the tank in 3 hours.   The answer is 3.
<result>B</result>
A pump can fill a tank with a water in 2 hours. Because of a leak, it took 6 hours to fill the tank. The leak can drain all the water of the full tank in how many hours?