Multiple choice

Four men or six children can do a piece of work in 12 days, working 7 hours a day. How many days will it take to complete a piece of work thrice as large as the first, with 12 men and 3 children working together 8 hours a day?

  1. 10

  2. 7

  3. 9

  4. 8

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

4 men = 6 children, so 1 man = 1.5 children. 12 men + 3 children = 12(1.5) + 3 = 18 + 3 = 21 children. Work 1: 6 children * 12 days * 7 hours = 504 man-hours. Work 2: 3 * 504 = 1512 man-hours. New group: 21 children * D days * 8 hours = 1512. D = 1512 / 168 = 9.

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