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

    Question

    ‘A’ alone can do some work in 12 days. ‘B’ and

    ‘C’ together can do the same work in 6 days. If ‘B’ is half as efficient as ‘A’, then find the time taken by ‘C’ to complete the work alone.
    A 5 days Correct Answer Incorrect Answer
    B 7 days Correct Answer Incorrect Answer
    C 9 days Correct Answer Incorrect Answer
    D 8 days Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let the total work be 12 units. {LCM (12 and 6)} So, efficiency of ‘A’ = (12/12) = 1 units/day So, efficiency of ‘B’ = (1/2) = 0.5 unit/day Efficiency of ‘B’ and ‘C’ together = (12/6) = 2 units/day So, efficiency of ‘C’ = 2 – 0.5 = 1.5 units/day So, time taken by ‘C’ to finish the work alone = (12/1.5) = 8 days

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