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

    Question

    ‘A’ alone can complete a work in 17 days. ‘B’

    alone can complete the same work in 34 days. If ‘A’ and ‘B’ work together for 5 days, then the remaining work can be completed by ‘A’ alone in how many days?
    A 7.5 days Correct Answer Incorrect Answer
    B 5.5 days Correct Answer Incorrect Answer
    C 9.5 days Correct Answer Incorrect Answer
    D 4.5 days Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let the total amount of work = 34 units {LCM of 17 and 34} Then, efficiency of ‘A’ = 34/17 = 2 units/day Efficiency of ‘B’ = 34/17 = 1 units/day Combined efficiency of ‘A’ and ‘B’ = 2 + 1 = 3 units/day Work completed by ‘A’ and ‘B’ together in 5 days = 3 × 5 = 15 units Remaining work = 34 – 15 = 19 units Time taken by ‘A’ alone to complete the remaining work = 19/2 = 9.5 days

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