Question

    Working alone, B can complete the work in 33 days. C is

    thrice 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 13 such works?
    A 70 days Correct Answer Incorrect Answer
    B 60 days Correct Answer Incorrect Answer
    C 87 days Correct Answer Incorrect Answer
    D 63 days Correct Answer Incorrect Answer
    E 78 days Correct Answer Incorrect Answer

    Solution

    Time taken by B to complete the work = 33 days
    Time taken by C to complete the work = 33/3 = 11 days
    Time taken by A to complete the work alone = 11 + 10 = 21 days
    Work done by A, B and C together in 1 day.
    ⇒ (1/33 + 1/11 + 1/21) = (7 + 21 + 11)/231 = 39/231
    this means if would take 231/39 days for A, B and C to complete the work together
    ∴ Time taken A, B and C to complete 13 works = 13 × 231/39 days = 77 days

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