Question 336947
A window washer can wash the windows on one side of a building in 72 working hours.
W W DATA:
time = 72 hrs/job
rate = 1/72 job/hr
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 With an assistant he can do the job in 40 hours.
Together DATA:
time = 40 hrs/job
rate = 1/40 job/hr
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Assistant DATA:
time = x hrs/job
rate = 1/x job/hr
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How many hours would the assistant take to do the job working alone?
Equation:
rate + rate = together rate
1/72 + 1/x = 1/40
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Multiply thru by 40*72x to get:
40x + 40*72 = 72x
32x = 40*72
x = 90 hrs (time the assistant would need to do the job alone)
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Cheers,
Stan H.
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