Question

    Average of 8 numbers is 30. If average of first four and last two numbers is 20 and 50, respectively then find the fifth number given that ratio of fifth and sixth number is 7:5, respectively.

    A 45 Correct Answer Incorrect Answer
    B 25 Correct Answer Incorrect Answer
    C 55 Correct Answer Incorrect Answer
    D 35 Correct Answer Incorrect Answer

    Solution

    Let fifth and sixth numbers be ‘7x’ and ‘5x’, respectively. So, 7x + 5x = 30 × 8 – 20 × 7 – 50 × 5 = 60 Or, 12x = 60 Or, x = 5 So, fifth number = 5 × 7 = 35

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