New Enroll in RBI Grade B New Batch - Starts on May 21

    Question

    A work can be completed by ‘A’ and ‘B’, alone in

    14 days and 7 days, respectively. Find the number of days taken by ‘C’ to complete the same work alone if ‘A’, ‘B’ and ‘C’ together can complete the whole work in 2 days.
    A 3.2 days Correct Answer Incorrect Answer
    B 3.7 days Correct Answer Incorrect Answer
    C 3.5 days Correct Answer Incorrect Answer
    D 2.5 days Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let total work = 14 units (LCM of 14 and 7) Efficiency of ‘A’ = (14/14) = 1 units/day Efficiency of ‘B’ = (14/7) = 2 units/day Combined efficiency of ‘A’, ‘B’ and ‘C’ = (14/2) = 7 units/day Efficiency of ‘C’ = 7 – (1 + 2) = 4 units/day Required time taken = (14/4) = 3.5 days

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