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

    Question

    ‘A’ alone can complete a work in 35 days while

    ‘A’ and ‘B’ together can complete the same work in 20 days. How much percentage of the work, ‘B’ alone can complete in 28 days?
    A 50% Correct Answer Incorrect Answer
    B 65% Correct Answer Incorrect Answer
    C 66% Correct Answer Incorrect Answer
    D 55% Correct Answer Incorrect Answer
    E 60% Correct Answer Incorrect Answer

    Solution

    Let the total work = L.C.M of 35 and 20 = 140 units Then, efficiency of ‘A’ alone = 140 ÷ 35 = 4 units/day Combined efficiency of ‘A’ and ‘B’ = 140 ÷ 20 = 7 units/day So, efficiency of ‘B’ = 7 – 4 = 3 units/day So, work done by ‘B’ alone in 28 days = 3 × 28 = 84 units So, percentage of work completed by ‘B’ = (84 ÷ 140) × 100 = 60%

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