Multiple choice

9 men and 6 boys together can do a piece of work in 18 days. A boy takes double time to complete the work as compared to a man. In how many days can 8 men do the complete work?

  1. 26 days

  2. 27 days

  3. 29 days

  4. 24 days

  5. 21 days
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let a man's 1-day work = m. Since a boy takes double time, a boy's 1-day work = m/2. Combined work: 9m + 6(m/2) = 9m + 3m = 12m per day. In 18 days, total work = 12m x 18 = 216m. Time for 8 men: 216m / 8m = 27 days. The key insight is that a boy is half as efficient as a man.

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