A cistern which could be filled in 9 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?
Pick
A) 22  B) 27  C) 29  D) 90  E) 12
1/9 - 1/x = 1/10   =&gt; 90 hrs   Answer: 90
<result>D</result>
A cistern which could be filled in 9 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?