Question

An electric pump can fill a tank in 3 hours. Because of a leak in the tank, it took 7/2 hours to fill the tank. The leak can drain out all the water of the tank in:

• A. 10:30 hrs
• B. 12 hrs
• C. 21 hrs
• D. 24 hrs

Answer 1

The correct option is C 21 hrs

Work done by the leak in 1 hour
$=(\frac{1}{3}-\frac{2}{7})=\frac{1}{21}$
$\therefore$ Leak will empty the tank in 21 hours.