Question
1 man and 3 boys can together complete a work in 20
days. 2 men and 3 boys can together complete the same work in 15 days. Find the time taken by 6 boys together to complete the entire work.Solution
Let the efficiency of a boy be 'B' units/day and the efficiency of a man be 'M' units/day we have, (1M + 3B) X 20 = (2M + 3B) X 15 Or, 20M + 60B = 30M + 45B Or, 15B = 10M So, B:M = 2:3 So, let B = '2a' and M = '3a' Total work = (1 X 3a + 3 X 2a) X 20 = '180a' units So, time taken by 6 boys together to complete the work = 180a Ă· (6 X 2a) = 15 days
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