How long will take a leak at the bottom of a tank to empty it if it will take
8 hours to fill it without the leak, but due to the leak it will take 9 hours to be filled? Choose the most appropriate option
A) 50 hours  B) 33 hours  C) 72 hours  D) 82 hours  E) 92 hours

Rationale: part filled without leak in 1 hour = 1 / 8 part filled with leak in 1 hour = 1 / 9 work done by leak in 1 hour = 1 / 8 â ˆ ’ 1 / 9 = 72 hours answer : c
Answer: C