Question

    Average of 8 numbers is 70. If average of first four and

    last two numbers is 80 and 45, respectively then find the fifth number given that ratio of fifth and sixth number is 4:1, respectively.
    A 110 Correct Answer Incorrect Answer
    B 150 Correct Answer Incorrect Answer
    C 120 Correct Answer Incorrect Answer
    D 130 Correct Answer Incorrect Answer

    Solution

    Let fifth and sixth numbers be ‘4x’ and ‘x’, respectively. So, 4x + x = 70 × 8 – 80 × 4 – 45 × 2 = 150 Or, 5x = 150 Or, x = 30 So, fifth number = 30 × 4 = 120

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