An electric pump can fill a tank in 6 hours. Because of a leak in the tank, it took 12hours to fill the tank. If the tank is full, how much time will the leak take to empty it? Pick:  A) 10 hours  B) 12 hours  C) 8 hours  D) 5 hours  E) 15 hours

Rationale: "work done by the leak in 1 hour = 1 / 6 - 1 / 12 = 1 / 12 the leak will empty the tank in 12 hours answer is b"
Answer: B