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Question 370506: Crew A can clean the Megadome in eight hours and Crew B can clean it in twelve hours. After a night game, crew A began a cleanup at midnight and was joined by crew B at 2:00 A.M. When was the job completed?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Crew A can clean the Megadome in eight hours and Crew B can clean it in twelve hours. --------------------------
A rate = 1/8 job/hr
B rate = 1/12 job/hr
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After a night game, crew A began a cleanup at midnight and was joined by crew B at 2:00 A.M. When was the job completed?
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Let "x" be the number of hours they worked together
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Equation:
work done + work done = job done
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2(1/8) + (1/8 + 1/12)x = 1 job
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1/4 + (20/(8*12))x = 1
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1/4 + (5/24)x = 1
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(5/24)x = 3/4
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x = (3/4)(24/5)
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x = 18/5 hrs.
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x = 3.6 hrs
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x = 3hr 36 minutes
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Hour Answer: Job completed at 5:36 AM
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Cheers,
Stan H.
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