SOLUTION: Water pours into a container at a constant rate of 4 liters per minute. When there are 50 liters of water in the container, a pump begins to pump water out at a rate of 5 liters pe

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Water pours into a container at a constant rate of 4 liters per minute. When there are 50 liters of water in the container, a pump begins to pump water out at a rate of 5 liters pe      Log On


   

Question 290209: Water pours into a container at a constant rate of 4 liters per minute. When there are 50 liters of water in the container, a pump begins to pump water out at a rate of 5 liters per minute. How many minutes will it take to empty the container?
(A)10 (B) 24 (C) 50 (D) 120 (E) None of these

Answer by vleith(2983) About Me  (Show Source):
You can put this solution on YOUR website!
The amount of water in the container can be modeled by this equation
WaterInContainer+=+50+%2B+%28AmountAddedPerMinute+-+AmountPumpedOutPerMinute%29+%2A+minutes or
w+=+50+%2B+%284+-+5%29+m
w+=+50+-+m
so when will the container be empty? It is empty when w = 0
0+=+50+-+m
-50+=+-m
50+=+m
50 minutes and the container is dry