A water tank which could be filled in 5 hours takes one more hour to be filled as a result of a leak in its bottom. If the tank is full calculate the time it will take for the leak empty it?	Choose the correct answer.
A) 32 hours
B) 30 hours
C) 34 hours
D) 31 hours
E) 33 hours

Rationale: part filled without leak in 1 hour = 1 / 5 part filled with leak in 1 hour = 1 / 6 work done by leak in 1 hour = 1 / 5 â ˆ ’ 1 / 6 = 30 hours answer : b
Answer: B