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    Question

    A can complete a work in 5 minutes, B in 6 minutes and C

    in 8 minutes. The average number of work completed per hour per worker for all three workers is:
    A 56/9 Correct Answer Incorrect Answer
    B 57/5 Correct Answer Incorrect Answer
    C 52/3 Correct Answer Incorrect Answer
    D 59/6 Correct Answer Incorrect Answer

    Solution

    Taking LCM of 5, 6 and 8  = 120 units Efficiency of A = 120/5 = 24 Efficiency of B = 120/6 = 20 Efficiency of C = 120/8 = 15 Time by which all complete the work together = 120/(24 + 20 + 15) = 120/59 mins Work completed in 1 min = 59/120 Then, work completed in 1 hour = 59 × 60/120 = 59/2 Average work completed per hour per worker = (59/2) ÷ 3 = 59/6 ∴ The required average is 59/6.

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