Question
Person A can complete 25% of a job in 4 days. Person B is
20% less efficient than Person A. How many days will it take for both A and B, working together, to complete 90% of the job?Solution
‘A’ can complete whole work alone in 4/0.25 = 16 days
‘B’ can complete the whole work in = 16/0.80 = 20 days
Let the total work = 80 units
Efficiency of ‘A’ = 80/16 = 5 units/day
Efficiency of ‘B’ = 80/20 = 4 units/day
Required time taken = 0.9 × 80/(5 + 4) = 8 days
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