A pump can fill a tank with water in 5 hours. Because of a leak, it took 10 hours to fill the tank. The leak can drain all the water in ?  Options:
A) 12hr
B) 11hr
C) 13hr
D) 10hr
E) 16hr
Work done by the leak in 1 hour = 1/5 - 1/10 = 1/10   Leak will empty the tank in 10 hours   Answer is 10hr
<result>D</result>
A pump can fill a tank with water in 5 hours. Because of a leak, it took 10 hours to fill the tank. The leak can drain all the water in ?