A pipe can fill a cistern in 20 minutes whereas the cistern when full can be emptied by a leak in 28 minutes. When both are opened,the time taken to fill the cistern is:
Let the capacity of the cistern be 140 units.
Efficiency of pipe = 140/20 = 7 units per minute
Efficiency of leakage = 140/-28 = -5 units per minute
Then, When both are opened, the cistern can be filled at 2 units per minute.
Therefore, 140 units can be filled in 140/2 = 70 minutes.
Create a FREE account and get:
