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    Question

    126 unit of work can be completed by P alone in 21 days.

    P started working alone and joined by Q after 10 days such that they completed the remaining work in 4 days. Find the number of days taken by Q to complete the whole work alone.
    A 30 days Correct Answer Incorrect Answer
    B 46 days Correct Answer Incorrect Answer
    C 13.5 days Correct Answer Incorrect Answer
    D 14 days Correct Answer Incorrect Answer
    E 12 days Correct Answer Incorrect Answer

    Solution

    Let the efficiency of Q = x units/day Efficiency of P = (126/21) = 6 units/day According to question: 6 × 10 + (6 + x) × 4 = 126 Or, 60 + 24 + 4x = 126 Or, 4x = 126 – 84 Or, 4x = 42 Or, x = 10.5 Number of days taken by Q to complete the work alone = (126/10.5) = 12 days

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