Four identical pumps can pump out all the water from a reservoir in 2 hours 18 minutes. How many of the same pumps

Four identical pumps can pump out all the water from a reservoir in 2 hours 18 minutes. How many of the same pumps need to be added so that all the water can be pumped out in 1 hour 32 minutes?

1. To begin with, for the convenience of calculations, let’s translate the data of time periods into minutes (1 hour = 60 minutes):

2 hours 18 minutes = 2 * 60 + 18 = 120 + 18 = 138 minutes;

1 h 32 min = 60 * 1 + 32 = 92 min.

2. Let’s calculate how long it takes to pump out all the water from the reservoir with only one pump, if 4 such pumps pump out water in 138 minutes:

138 * 4 = 552 (min).

3. Now we will find how many pumps are needed to keep within 92 minutes:

552/92 = 6 (s.).

4. That is, you need to add:

6 – 4 = 2 (us).

Answer: you need to add 2 such pumps.