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

    Question

    A is twice as efficient as B at completing a task, and

    together they can finish the task in 20 days. How many days would A alone take to complete the task?
    A 34 days Correct Answer Incorrect Answer
    B 30 days Correct Answer Incorrect Answer
    C 28 days Correct Answer Incorrect Answer
    D 32 days Correct Answer Incorrect Answer

    Solution

    A is twice as efficient as B, and together they can complete a task in 20 days.   Let B's work rate be x.   A's work rate is 2x.   Combined work rate of A and B: 2x + x = 3x.   Together they complete the task in 20 days: 3x = 20     x = 1 /60   A's work rate is 2x=2× 1 /60 =1 /30 =30days

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