A pipe can fill a tank in 6 hours. Due to a leak in its bottom, it is filled in 7 hours. If the tank is full, then the time it will take to empty it because of the leak is:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 42 hours
In one hour the pipe alone fills \( \frac{1}{6} \) of the tank, while the pipe with the leak fills only \( \frac{1}{7} \). The difference is the part the leak empties in one hour:
\( \displaystyle \text{Leak's rate}=\frac{1}{6}-\frac{1}{7} \)
\( \displaystyle =\frac{7-6}{42} \)
\( \displaystyle =\frac{1}{42}\ \text{of the tank per hour} \)
So the leak empties a full tank in 42 hours.