Answer:
It will take both pumps 3.08 hours to fill the tank working together.
Explanation:
Pump A can fill the tank in 5 hours. Assuming that the pump gives out a steady flow of water, in one hour, pump A can fill 1/5th of the tank. Similarly, pump B in an hour, fills up 1/8th of the tank.
We must add up these two values, in order to find how much of the tank the two pumps can fill up together in one hour.
1/5 +1/8 =13/40
So 13/40 of the tank is filled in an hour. We need to find how many hours it will take for the entire tank to be filled. To do so, divide 40 by 13. This gives:
3.08 hours to fill up the tank.
