A cistern is fille in 8 hours and it takes 12 hours when there is a leak in its bottom. If the cistern is full, in what time shall the leak empty it?
Choose the correct choice from the following options:	A) 22 hours	B) 21 hours	C) 24 hours	D) 23 hours	E) 25 days
Explanation:   work done by 1 hour by filling pipe = 1/8   work done by 1 hour by the leak and the filling pipe =1/12   work done by 1 hour by the leak = 1/8 – 1/12 =1/24   Hence the leak can empty it in 24 hours.   Answer: Option 24 hours
<result>C</result>
A cistern is fille in 8 hours and it takes 12 hours when there is a leak in its bottom. If the cistern is full, in what time shall the leak empty it?