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 ?
A
19 hours
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B
1 hours
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C
90 hours
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D
35 hours
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Solution
The correct option is C90 hours The cistern is filled in 9 hrs.
∴ In 1 hour, 19 part of the cistern will be filled.
Again, it takes (9+1) hours =10 hrs. to fill the cistern due to a leak.
∴ In 1 hour, 110 part of the cistern will be filled when it leakes.
So, in 1 hour 19−110 part
=190 part will be emptied.
∴ The full cistern will be emptied in 1190 hour =90 hour.