SOLUTION: It takes an older pump 3 times as long to drain a certain pool as it does a newer pump. Working together, it takes the two pumps 9 hours to drain the pool. How long will it take t

Algebra ->  Rate-of-work-word-problems -> SOLUTION: It takes an older pump 3 times as long to drain a certain pool as it does a newer pump. Working together, it takes the two pumps 9 hours to drain the pool. How long will it take t      Log On


   

Question 1152252: It takes an older pump 3 times as long to drain a certain pool as it does a newer pump. Working together, it takes the two pumps 9 hours to drain the pool. How long will it take the older pump to drain the pool working alone?
Found 2 solutions by josgarithmetic, greenestamps:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Rate for old pump 1%2F3t
Rate for new pump 1%2Ft
Rate for both pumps combined 1%2F9

1%2F%283t%29%2B1%2Ft=1%2F9-----------solve and find the value of 1%2F3t.

Answer by greenestamps(13198) About Me  (Show Source):
You can put this solution on YOUR website!


Since it takes the older pump 3 times as long as the newer pump to drain the pool, when working together the newer pump does 3/4 of the work and the older pump does 1/4.

Then, since the older pump drains 1/4 of the pool in those 9 hours when the pumps are both working, it will take the older pump 4*9 = 36 hours to drain the pool alone.