Question

    Working alone, B can complete the work in 30 days. C is

    thrice as efficient as B and A takes 5 days more than it takes C to complete the work. Working together, in how much time would they be able to complete 4 such works?
    A 10 days Correct Answer Incorrect Answer
    B 20 days Correct Answer Incorrect Answer
    C 17 days Correct Answer Incorrect Answer
    D 13 days Correct Answer Incorrect Answer
    E 18 days Correct Answer Incorrect Answer

    Solution

    Time taken by B to complete the work = 30 days
    Time taken by C to complete the work = 30/3 = 10 days
    Time taken by A to complete the work alone = 10 + 5 = 15 days
    Work done by A, B and C together in 1 day.
    ⇒ (1/30 + 1/10 + 1/15) = (1 + 3 + 2)/30 = 6/30
    this means if would take 30/6 days for A, B and C to complete the work together
    ∴ Time taken A, B and C to complete 4 works = 4 × 30/6 days = 20 days

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