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

    Question

    ‘A’ alone can complete a work in 40 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 30 days?
    A 72% Correct Answer Incorrect Answer
    B 73% Correct Answer Incorrect Answer
    C 75% Correct Answer Incorrect Answer
    D 77% Correct Answer Incorrect Answer

    Solution

    Let the total work = L.C.M of 40 and 20 = 40 units Then, efficiency of ‘A’ alone = 40 ÷ 40 = 1 units/day Combined efficiency of ‘A’ and ‘B’ = 40 ÷ 20 = 2 units/day So, efficiency of ‘B’ = 2 – 1 = 1 units/day So, work done by ‘B’ alone in 30 days = 1 × 30 = 30 units So, percentage of work completed by ‘B’ = (30 ÷ 40) × 100 = 75%

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