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    Question

    The time taken by ‘A’ to complete a task is 6 days

    more than the time taken by A and B together. If A is twice as efficient as B, find the time required by B to complete the work alone.
    A 22 days Correct Answer Incorrect Answer
    B 18 days Correct Answer Incorrect Answer
    C 36 days Correct Answer Incorrect Answer
    D 42 days Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    ATQ,

    Let the time taken by A and B together to complete the work be ‘n’ days. Time taken by A alone = (n + 6) days Time taken by B alone = 2 × (n + 6) days (since A is twice as efficient as B) Now, 1/(n + 6) + 1 / [2(n + 6)] = 1/n ⇒ 3 / [2(n + 6)] = 1/n ⇒ 3n = 2n + 12 ⇒ n = 12 Therefore, time taken by B alone = 2 × (12 + 6) = 2 × 18 = 36 days

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