Question

    ‘A’ alone can do some work in 10 days. ‘B’ and

    ‘C’ together can do the same work in 4 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 4 days Correct Answer Incorrect Answer
    C 7 days Correct Answer Incorrect Answer
    D 10 days Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let the total work be 20 units. {LCM (10 and 4)} So, efficiency of ‘A’ = (20/10) = 2 units/day So, efficiency of ‘B’ = (2 x 0.5) = 1 unit/day Efficiency of ‘B’ and ‘C’ together = (20/4) = 5 units/day So, efficiency of ‘C’ = 5 – 1 = 4 units/day So, time taken by ‘C’ to finish the work alone = (20/4) = 5 days

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