Question
‘A’ alone can complete a work in 35 days while
‘A’ and ‘B’ together can complete the same work in 20 days. How much percentage of the work, ‘B’ alone can complete in 28 days?Solution
Let the total work = L.C.M of 35 and 20 = 140 units Then, efficiency of ‘A’ alone = 140 ÷ 35 = 4 units/day Combined efficiency of ‘A’ and ‘B’ = 140 ÷ 20 = 7 units/day So, efficiency of ‘B’ = 7 – 4 = 3 units/day So, work done by ‘B’ alone in 28 days = 3 × 28 = 84 units So, percentage of work completed by ‘B’ = (84 ÷ 140) × 100 = 60%
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