How long will it take to empy the retention pond?

Question

Three pumps are used to empty retention Pond holding an unknown amount of water. If pump 1 can empty the pond in 4 days, pump 2 can empty the pond in 10 days, and Pump 3 can empty the pond and 5 days, how many days will it take to empty the pond if all pumps for running at the same time?

Answer 1

pump 1 has a rate of .25 ponds per day

pump 2 is .10 ponds per day

pump three is .2 ponds per day.

 

so all three combined run .55 ponds per day with will take 1 day, 10 hours and 48 minutes.