A pipe can fill an overhead tank in 12 hours. But due to a leak at the bottom, it is filled in 18 hours. If the tank is full, how much time will the leak take to empty it?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is Option 4 i.e. 36 hours.
Given that, the time taken by filling the pipe to fill the tank = 12 hours
Time taken by a filling pipe and leakage to fill the tank = 18 hours
Let the total work to be done by both pipes LCM(12, 18) be 36 units.
Total work = Efficiency × Time taken
Efficiency of filling pipe = = 3 units/hour
Efficiency of both filling pipe and leakage = = 2 units/hour
⇒ Efficiency of leakage = 3 - 2 = 1 unit/hour
Time taken by the leakage to empty the filled tank = = 36 hours
Hence the required answer is 36 hours.