Q:
Concept of Efficiency
A can do a job in 12 days and B can do the same job in 6 days, in how many days working together they can complete the job?
Answer
A's 1 days work = 1/12
B's 1 days work =1/6
Therefore, (A+B)'s 1 day's work= 1/12 + 1/6 = 1/4
Therefore, Time taken by both to finish the whole work = = 4 days
Alternatively :
Efficiency of A =100/12 =8.33%
Efficiency of B =100/6=16.66%
Combined efficiency of A and B both = 8.33+16.66=25%
Therefore, Time taken by both to finish the work (working together) =100/25= 4days
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