Question

It takes 2hrs to fill the tank. there is leakage in tank and now it takes 2hrs 20 mins to fill the tank. then in how much time will the tank empty .{ans is 14 hrs I want theory behind this question that how the answer is derived .}

Answer 1

Let the volume of tank be 1 unit. We have, rate of filling the tank without a leak = 1 unit per 2 hours. And the rate of filling in the presence of a leak = 1 unit per 2 hours 20 minutes = 1 unit per 7/3 hours. Now, the rate of emptying the tank = 1/2 - 1/(7/3) =1 unit per 14 hours. Then, time taken to empty the tank = 14 hours