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Question 66831: A sewage treatment plant has two inlet pipes to its settling pond.
One can fill the pond in 10 hours, the other in 12 hours. If the first
pipe is open for 5 hours and then the second pipe is opened, how long
will it take to fill the pond?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! A sewage treatment plant has two inlet pipes to its settling pond.
One can fill the pond in 10 hours, the other in 12 hours. If the first
pipe is open for 5 hours and then the second pipe is opened, how long
will it take to fill the pond?
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1st pipe DATA:
Time to fill = 10 hr/job ; Rate = (1/10)job/hr
If 1st pipe is open 5 hours it completes (1/2) of the job.
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2nd pipe DATA:
Time to fill = 12 hr/job ; Rate = (1/12)job/hr
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EQUATION:
Let x be the number of hours the pipes are working to finish filling the tank.
x(1/10)+1/12)= (1/2) job
x(22/120)=1/2
x=120/44
x=30/11
x=2.7272... hrs to finish filling the tank.
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