A pump can fill a tank with water in 2 hours. Because of a leak, it took 7 hours to fill the tank. The leak can drain all the water in ?  Choose the correct choice from the following.
A) 15hr 10min	B) 16hr 20min	C) 2hr 48min	D) 15hr	E) 14hr 25min
Work done by the leak in 1 hour = 1/2 - 1/7 = 5/14   Leak will empty the tank in 14/5 hrs = 2hr 48min   Answer is 2hr 48min
<result>C</result>
A pump can fill a tank with water in 2 hours. Because of a leak, it took 7 hours to fill the tank. The leak can drain all the water in ?