<PRE><B>Question 89862</B>
One grocery clerk can stock a shelf in 30 minutes, wheras a second clerk requires 45 minutes to do the same job. If the two clerks worked together, how many minutes would it take to stock the shelf? 

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1st clerk DATA:
Time = 30 min/job ; Rate = 1/30 job/min
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2nd clerk DATA:
Time = 45 min/job ; Rate = 1/45 job/min
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Working together DATA:
Time = x min/job ; Rate = 1/x job/min
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EQUATION:
rate + rate = together rate
1/30 + 1/45 = 1/x
Multiply thru by 90x to get:
3x + 2x = 90
5x = 90
x = 18 minutes (time for the job for the two working together)
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Cheers,
Stan H. </PRE>