SOLUTION: Machine A can do a certain job in 8 hours. machine B can do the same job in 10 hours. machine C can do the same job in 12 hours. all three machines start the job at 9.00 am, machin

Question 1064559: Machine A can do a certain job in 8 hours. machine B can do the same job in 10 hours. machine C can do the same job in 12 hours. all three machines start the job at 9.00 am, machine B breaks down at 11.00am and the other two machines finish the job. approximately at what time would the job be completed?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Machine A can do a certain job in 8 hours. machine B can do the same job in 10 hours. machine C can do the same job in 12 hours. all three machines start the job at 9.00 am, machine B breaks down at 11.00am and the other two machines finish the job. approximately at what time would the job be completed?
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A time = 8 hrs/job ; A rate = 1/8 job/hr
B time = 10 hrs/job ; B rate = 1/10 job/hr
C time = 12 hrs/job ; C rate = 1/12 job/hr
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Equations:
Let x be the hours to do the job::
work + work + work = 1 job
(1/8)x + 2(1/10) + (1/12)x = 1 job
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Multiply thru by 120 to get:
15x + 24 + 10x = 120
25x = 96
x = 3.84 hrs = 3hrs 50 min 24 seconds
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Cheers,
Stan H.
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