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

    Question

    ‘A’ alone can complete a work in 12 days. ‘B’

    alone can complete the same work in 20 days. If ‘A’ and ‘B’ work together for 6 days, then the remaining work can be completed by ‘A’ alone in how many days?
    A 3.4 days Correct Answer Incorrect Answer
    B 4.4 days Correct Answer Incorrect Answer
    C 3.75 days Correct Answer Incorrect Answer
    D 2.4 days Correct Answer Incorrect Answer

    Solution

    Let the total amount of work = 60 units {LCM of 12 and 20} Then, efficiency of ‘A’ = 60/12 = 5 units/day Efficiency of ‘B’ = 60/20 = 3 units/day Combined efficiency of ‘A’ and ‘B’ = 5 + 3 = 8 units/day Work completed by ‘A’ and ‘B’ together in 6 days = 6 × 8 = 48 units Remaining work = 60 – 48 = 12 units Time taken by ‘A’ alone to complete the remaining work = 12/5 = 2.4 days

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