A pump can normally fill a sump in 6 hours. Because of a leak, it now takes 8 hours to fill. If the sump is full and the pump is off, how long will the leak take to empty it?

Explanation

1. 01

   Pump alone: $\frac{1}{6}$ per hour. Pump with leak: $\frac{1}{8}$ per hour.

2. 02

   Leak's rate = $\frac{1}{6} - \frac{1}{8} = \frac{4-3}{24} = \frac{1}{24}$.

3. 03

   The leak empties the full sump in 24 hours.