SajjadAhmad wrote:

A swimming pool is supplied water by two pipes, P and Q. If pipe P operating alone can fill the pool in 12 hours, how long will it take pipe Q operating alone to fill the pool?

(1) Operating together, pipes P and Q can fill the pool in 4 hours.

(2) Pipe P supplies water at the rate of 520 gallons per hour, and 6240 gallons are required to fill the pool.

(1) We are given that pipe P alone fills 1/12 fraction of the pool every hour, and together pipe P and Q fill 1/4 fraction of the pool every hour. So on the basis of this information we can find the fraction supplied by pipe Q (it will be 1/4 - 1/12 = 1/6). This in turn, will give us the time required by pipe Q alone to fill the pool.

Sufficient.

(2) This statement gives no information about pipe Q,

insufficient.

Hence

A answer