Question

A pipe can fill a cistern in $9$ hours. Due to a leak in its bottom, the cistern fills up in $10$ hours. If the cistern is full, in how much time(in hours) will it be emptied by the leak?

Answer 1

A pipe can fill in $9hrs$ work done will be $\frac{1}{9}$

Cistern fills up in $10hrs$ if there is a leak. So work will be done in $\frac{1}{10}$

Time taken to empty the cistern

$=\frac{1}{9}-\frac{1}{10}$

$=\frac{10-9}{90}$

$=\frac{1}{90}$

It will be emptied in $90hrs$