A cistern which could be filled in 9 hours takes 1 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?  Choose the most appropriate option:  A) 50hours  B) 62hours  C) 90hours  D) 75hours  E) 100hours
Let the leak empty the full cistern in x hours   9x/x-9 = 9+1   x = 90 hours   Answer is 90hours
<result>C</result>
A cistern which could be filled in 9 hours takes 1 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?