A cistern which could be filled in 5 hours takes one hour more to be filled owing to a leak in its bottom. If the cistern is full in what time will the leak empty it?
Answers:	A) 76 hrs	B) 99 hrs	C) 55 hrs	D) 90 hrs	E) 10 hrs
1/5 - 1/x = 1/10   =&gt; 10 hrs   Answer: 10 hrs
<result>E</result>
A cistern which could be filled in 5 hours takes one hour more to be filled owing to a leak in its bottom. If the cistern is full in what time will the leak empty it?