Expert: Ahmed Salami - 5/6/2009

Question
The water from one outlet, flowing at a constant rate, can fill a swimming pool in 9 hrs.The water from a second outlet, flowing at a constant rate, can fill the same pool in 5 hrs.If both outlets are used at the same time, approximately what is the number of hours required to fill the pool?

Answer
Hi Shruti,
In one hour, first outlet fills 1/9 of the pool and second outlet fills 1/5 of the pool. This means that the two outlets fill 1/9 + 1/5 = 14/45 of the volume of the pool.
The time it takes to fill the whole pool is therefore 1/(14/45) hours
= 45/14 hours
= 3.2 hours

Regards