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P, Q and R can complete a work in 24, 6 and 12 days respectively. The work will be completed in________days if all of them are working together.

Correct answer: B. 3 3⁄7

  • A. 2
  • B. 3 3⁄7
  • C. 4 ¼
  • D. 5Election Officer Mcqs

Explanation

Their combined daily rate is 1/24 + 1/6 + 1/12 = 1/24 + 4/24 + 2/24 = 7/24 work per day. Therefore the time is 1 / (7/24) = 24/7 = 3 3/7 days. The likely mistake is 4 1/4 days, which may come from adding the completion times rather than the rates.

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About Time and Work

Problems measure work through rates, treating each person's or machine's contribution as work completed per unit time. Questions cover combined work, efficiency, wages, alternate working schedules, pipes and cisterns, and men-days relationships, with care needed to distinguish time taken by one worker from the time required when workers act together.

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