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    Question

    A alone can complete a work in 20 days and S alone can

    complete the same work in 30 days. They start the work together, but S left the work 5 days before the completion of work. In how many days, will the work completed?
    A 15 Days Correct Answer Incorrect Answer
    B 17 days Correct Answer Incorrect Answer
    C 14 days Correct Answer Incorrect Answer
    D 20 days Correct Answer Incorrect Answer

    Solution

    ATQ, Per day efficiency of A = 1/20 Per day efficiency of S = 1/30 Working together, per day efficiency = (1/20) + (1/30) = (3 + 2)/60 = 5/60 = 1/12 Let together they worked for d days Then, total work gets completed in (d + 5) days [(d/12) + (5/20)] = 1 ⇒ d/12 = 3/4 ⇒ d = 9 Now, d + 5 = 14 ∴ Total work gets completed in 14 days.

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