An electric pump can fill a tank in 4 hours. Because of a leak in the tank, it took 8hours to fill the tank. If the tank is full, how much time will the leak take to empty it?  Choose the correct choice from the following answers:
A) 10hours
B) 12hours
C) 8hours
D) 5hours
E) 15hours
Work done by the leak in 1 hour = 1/4 - 1/8 = 1/8   The leak will empty the tank in 8hours   Answer is 8hours
<result>C</result>
An electric pump can fill a tank in 4 hours. Because of a leak in the tank, it took 8hours to fill the tank. If the tank is full, how much time will the leak take to empty it?