It takes 3 hours to fill a tank but due to a leakage it takes 4 hours

It takes 3 hours to fill a tank but due to a leakage it takes 4 hours. How long would the leak take to empty a full tank?

  1. 18 hours
  2. 16 hours
  3. 12 hours
  4. 10 hours

Answer

Time taken by tap to fill the tank = 3 hours

Time take by leak = x hours

Per hour : tap= 1/3, Leak = 1/x

part of the tank filled in 1 hour = 1/4 = 1/3 = 1/x

therefor, 1/x = 1/3-1/4 = 1/12

x = 1/12

The correct option is C.