SOLUTION: 2 pipes can fill up a water tank is 6hrs and 40min find the time each will take to fill the tank if one of the two pipes can fill it is 3hrs less than the other
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Question 734330: 2 pipes can fill up a water tank is 6hrs and 40min find the time each will take to fill the tank if one of the two pipes can fill it is 3hrs less than the other Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! 2 pipes can fill up a water tank is 6hrs and 40min find the time each will take to fill the tank if one of the two pipes can fill it is 3hrs less than the other
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one pipe: time = x hrs/job ; rate = 1/x job/hr
other pipe: time = x-3 hrs/job ; rate = 1/(x-3) job/hr
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together: time = 6 2/3 hrs/job ; rate = 3/20 job/hr
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Equation:
rate + rate = together rate
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1/x + 1/(x-3) = 3/20
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Multiply thru by 20x(x-3) to get:
20(x-3) + 20x = 3x(x-3)
40x - 60 = 3x^2-9x
3x^2-49x + 60 = 0
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(x-15)(3x-4) = 0
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Usable solution:
x = 15 hrs (time for the slower pipe)
x-3 = 12 hrs (time for the faster pipe)
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Cheers,
Stan H.
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