How long will take a leak at the bottom of a tank to empty it if it will take 3 hours to fill it without the leak, but due to the leak it will take one additional hour to be filled? Choose the correct choice from the following answers
A) 12 hours
B) 111 hours
C) 15 hours
D) 14 hours
E) 11 hours

Rationale: part filled without leak in 1 hour = 1 / 3 part filled with leak in 1 hour = 1 / 4 work done by leak in 1 hour = 1 / 3 â ˆ ’ 1 / 4 = 12 hours answer : a
Answer: A