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Question 619929: Two pumps of different sizes, working together can empty a tank in five hours. The larger pump can empty this tank in four hours less than the smaller. If the larger pump is out of order, how long will it take the smaller one to do the job alone?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Two pumps of different sizes, working together can empty a tank in five hours. The larger pump can empty this tank in four hours less than the smaller. If the larger pump is out of order, how long will it take the smaller one to do the job alone?
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Together rate: 1/5 job/hr
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Larger pump rate: 1/x job/hr
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Smaller pump rate: 1/(x+4) job/hr
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Equation:
rate + rate = together rate
1/x + 1/(x+4) = 1/5
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Multiply thru by 5x(x+4) to get:
5(x+4) + 5x = x(x+4)
10x + 20 = x^2 + 4x
x^2 - 6x - 20 = 0
x = 8.3852 hrs
x+4 = 12.3852 hrs (time for the smaller pipe)
Cheers,
Stan H.
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