An electric pump can fill a tank in 3 hours. Because of a leak in the tank, it took 3 hours 30 min to fill the tank. The leak can drain out all the water of the tank in :
A. 10 hours 30 min
B. 21 hours
C. 12 hours
D. 24 hours
Answer:B
An electric pump can fill a tank in 3 hours. Because of a leak in the tank, it took 3 hours 30 min to fill the tank. The leak can drain out all the water of the tank in :
A. 10 hours 30 min B. 21 hours C. 12 hours D. 24 hours
Explanation: Work done by the leak in 1 hour = (1/3) - (2/7) = 1/21 .