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    Question

    Working alone, B can complete the work in 20 days. C is

    twice as efficient as B and A takes 10 days more than it takes C to complete the work. Working together, in how much time would they be able to complete 11 such works?
    A 77 days Correct Answer Incorrect Answer
    B 48 days Correct Answer Incorrect Answer
    C 55 days Correct Answer Incorrect Answer
    D 63 days Correct Answer Incorrect Answer
    E 75 days Correct Answer Incorrect Answer

    Solution

    Time taken by B to complete the work = 20 days
    Time taken by C to complete the work = 20/2 = 10 days
    Time taken by A to complete the work alone = 10 + 10 = 20 days
    Work done by A, B and C together in 1 day.
    ⇒ (1/20 + 1/10 + 1/20) = (1 + 2 + 1)/20 = 4/20
    this means if would take 20/4 days for A, B and C to complete the work together
    ∴ Time taken A, B and C to complete 11 works = 11 × 20/4 days = 55 days

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