# One pump can fill a water tank in 40 minutes and another pump takes 30 minutes? How long will it take to fill the water tank if both pumps work together?

##### 2 Answers

#### Explanation:

Let

Filling rate of first pump

Filling rate of second pump

If

Hence, the total time taken by both pumps to fill the tank is

#### Explanation:

To work this out we need to know the rate that the water is flowing with both pumps working.

Flow rate of pump1

Flow rate of pump1

So flow rate of pump 1 + pump 2

The reciprocal of rate is time so