If Sam can do a job in 4 days that Lisa can do in 6 days and Tom can do in 2 days, how long would the job take if Sam, Lisa, and Tom worked together to complete it?
A. 0.8 days
B. 1.09 days
C. 1.23 days
D. 1.65 days
E. 1.97 days
source: testpreppreview.com
From the information given, it can be concluded that: Sam can do 1/4 of the job in one day, Lisa can do 1/6 of the job in one day, and Tom can do 1/2 of the job in one day. In one day, if they work together they can complete 11/12(1/4+1/6+1/2) of the job. To finish the other 1/12 of the job, it will take 1/11 of the second day, because 1/11 times 11/12 is equal to the other 1/12 necessary to complete the job. If they worked together, it would take 1 1/11 days. The answer is (B).
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