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

    Question

    If person 'A' can complete a task in 35 hours and person

    'B' can complete the same task in 40 hours, how much time will it take for both 'A' and 'B' to complete 60% of the work when they work together?
    A 13.2 hours Correct Answer Incorrect Answer
    B 11.2 hours Correct Answer Incorrect Answer
    C 9.6 hours Correct Answer Incorrect Answer
    D 16 hours Correct Answer Incorrect Answer

    Solution

    Let the total work = L.C.M of 35 and 40 = 280 units Then, efficiency of 'A' = 280 ÷ 35 = 8 units/hour Efficiency of 'B' = 280 ÷ 40 = 7 units/hour 60% of the work = 280 X 0.6 = 168 units Time taken by 'A' and 'B' working together to complete 60% of the work = 168 ÷ (7 + 8) = 11.2 hours

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