Question

If one pump can empty a flooded basement in 18 hours, and a second pump can empty the basement in 20 hours, how long will it take it to empty the basement when both pumps are uses?

Answer 1

Answer: It would take approximately 9.47 hours.

Explanation:

Given : One pump can empty a flooded basement in 18 hours, and a second pump can empty the basement in 20 hour.

Let 't' be the time both of them together to fill the tank.

Now , the total time taken to empty the basement when both pumps are uses :-

`(1)/(t)=(1)/(18)+(1)/(20)\\\\\Rightarrow\ (1)/(t)=(10+9)/(180)\\\\\Rightarrow\ t=(180)/(19)\approx9.47`

Hence, it would take approximately 9.47 hours.