The pool is filled with water through two pipes, one pipe can fill the pool in 6 hours and the other

The pool is filled with water through two pipes, one pipe can fill the pool in 6 hours and the other in 18 hours. How long will it take for two pipes to fill the pool at the same time?

Let the conditional volume of the pool be equal to 1.

We find which part of the pool each of the two pipes fills per hour.

1/6 is the first pipe.

1/18 is the second pipe.

Let us determine the part of water that 2 pipes can fill during simultaneous operation.

To do this, we summarize the previously found parts.

1/6 + 1/18 = 3/18 + 1/18 = 4/18 = 2/9.

We determine the time of filling the pool through both pipes.

We divide the volume of water in the pool by the found total part.

1 / 2/9 = 1 * 9/2 = 4.5 hours.

Answer:

The pool will be filled in 4.5 hours.