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

    Question

    ‘A’ and ‘C’ together can dig a hole in 8 hours

    while ‘A’, ‘B’ and ‘C’ together can dig the same hole in 6 hours. Find the time taken by ‘B’ alone to dig the same hole.
    A 32 hours Correct Answer Incorrect Answer
    B 18 hours Correct Answer Incorrect Answer
    C 16 hours Correct Answer Incorrect Answer
    D 24 hours Correct Answer Incorrect Answer

    Solution

    Let the total work be 24 units {LCM (8 and 6)}
    Efficiency of ‘A’ and ‘C’ together = 24/8 = 3 units/hour
    Efficiency of ‘A’, ‘B’ and ‘C’ together = 24/6 = 4 units/hour
    Efficiency of ‘B’ = 4 – 3 = 1 unit/hour
    Time taken by ‘B’ to dig the same hole alone = (24/1) = 24 hours

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