Question

    Person A is 80% more efficient than person B. A and B

    together can complete a certain task in 10 days, while B and C together can complete the same task in 7 days. What is the ratio of the efficiency of A to that of C?
    A 5:6 Correct Answer Incorrect Answer
    B 6:5 Correct Answer Incorrect Answer
    C 3:5 Correct Answer Incorrect Answer
    D 4:5 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let the efficiency of 'B' be '5x' units/day
    So, efficiency of 'A' = 5x X 1.8 = '9x' units/day
    So, total work = 10 X (5x + 9x) = '140x' units
    So, combined efficiency of 'B' and 'C' = 140x ÷ 7 = '20x' units/day
    So, efficiency of 'C' = 20x - 5x = '15x' units/day
    So, required ratio = 9x:15x = 3:5

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