SOLUTION: a water pump fills a reservoir in 4 hours. Another pump empties the same reservoir in 8 hours. If both pumps are turned on accidentally, how long will it take to fill the empty res

Algebra ->  Percentage-and-ratio-word-problems -> SOLUTION: a water pump fills a reservoir in 4 hours. Another pump empties the same reservoir in 8 hours. If both pumps are turned on accidentally, how long will it take to fill the empty res      Log On


   



Question 441173: a water pump fills a reservoir in 4 hours. Another pump empties the same reservoir in 8 hours. If both pumps are turned on accidentally, how long will it take to fill the empty reservoir?
Answer by jorel1380(3719) About Me  (Show Source):
You can put this solution on YOUR website!
t/4-t/8=1
2t-t=8
t=8
It will take 8 hours to fill the reservoir.
1/4-1/8=1/t
2/8-1/8=1/t
1/8=1/t
t=8..