Question
'A' alone can do some work in 15 days, 'B' alone can do
the same work in 30 days. If they work on alternate days, starting with 'B', then the work will be finished in:Solution
Let the total work be 30 units {LCM (15 and 30)} So, efficiency of 'A' = 30 ÷ 15 = 2 units/day And efficiency of 'B' = 30 ÷ 30 = 1 unit/day Work done in every 2 days (B + A) = 1 + 2 = 3 units So, work done in 20 days by 'A' and 'B' = (20 ÷ 2) x 3 = 30 units Total time taken = 20 days
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