A pump can fill a tank with water in 2 hours. Because of a leak, it took 21/3 hours to to fill the tank. The leak can drain all the water of the tank in?

Answer: Option D

Work done by the leak in 1 hour
$$\begin{array}{rl}& \text{ = }\left(\frac{1}{2}-\frac{3}{7}\right)=\frac{1}{14}\end{array}$$
∴ Leak will empty the tank in 14 hours