An inlet pipe can fill an empty swimming pool in 5 hours, and another inlet pipe can fill the pool in 2 hours. How long will it take both pipes to fill the pool?

1.42 hours

Step-by-step explanation:

In this case we must take into account that the speed would be to fill a pool for a time, that this case is in hours, therefore it would be like this:

1/5 for the first pipe

1/2 for the second pipe

Now, we will use both at the same time, therefore:

1/5 + 1/2 = 1 / x

0.7 = 1 / x

x = 1 / 0.7

x = 1.42

That is to say that if we use both we will take a total of 1.42 hours