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Question 222878: Heather and marika recently worked at the community service day at Harvey Scott Elementary School. If it took them 3 hours working together to put bark dust down on the side of the school, and it would have taken Heather 5 hours to do it herslef, how long would it take Marika to complete the job by herself?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Heather and marika recently worked at the community service day at Harvey Scott Elementary School. If it took them 3 hours working together to put bark dust down on the side of the school, and it would have taken Heather 5 hours to do it herslef, how long would it take Marika to complete the job by herself?
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Together DATA:
time = 3 hr/job ; rate = 1/3 job/hr.
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Heather DATA:
time = 5 hr/job ; rate = 1/5 job/hr
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Marika DATA:
time = x hr/job ;rate = 1/x job/hr
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Equation:
rate + rate = together rate
1/5 + 1/x = 1/3
Multiply thru by 15x to get:
3x + 15 = 5x
2x = 15
x = 7 1/2 hrs (time for Marika to do the job alone)
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Cheers,
Stan H.
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