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 will it be emptied by the leak?
A pipe can fill a cistern in: 9 hours
Let a leak empty the cistern in: X hours
Due to the leak time taken to fill the cistern : 10 hours
Part of the cistern filled by pipe in one hour:
Part of the cistern emptied by leak in one hour:
=
=
=
X = 90 hours
Therefore the leak will empty the cistern in 90 hours.