Question 556002
The OfficeJet printer can copy Maria's dissertation in 8 minutes. The LaserJet printer can copy the same document in 12 minutes. If the two machines worked together, how long would they take to copy the dissertation? 
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Office Jet time = 8 min/job ; rate = 1/8 job/min
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Laser Jet time = 12 min/job ; rate = 1/12 job/min
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Together time = x min/job ; rate = 1/x job/min
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Equation:
rate + rate = together rate
1/8 + 1/12 = 1/x
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Multiply thru by 24x to get:
3x + 2x = 24
5x = 24
x = 4.8 minutes/job (time to do the job together)
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Cheers,
Stan H.
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