Problema Solution
Two people together can do a certain job in 20 minutes. If one of them can do the job alone in 45 minutes, how long will the other person take to do the job alone?
Answer provided by our tutors
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Together DATA:
Time = 20 min/job ; Rate = 1/20 job/min
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One person DATA:
Time = 45 min/job ; Rate = 1/45 job/min
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2nd person DATA:
Time = x min/job ; RAte = 1/x job/min
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EQUATION:
rate + rate = together rate
1/45 + 1/x = 1/20
Multiply thru by 180x to get:
4x + 180 = 9x
5x = 180
x = 36 min (time for the 2nd person to do the job alone)