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    Question

    The mean of 15 values is 72. The mean of the first seven

    values is 62, and the mean of the last five values is 86. The eighth value equals 25% of the ninth, and the tenth value is 75% more than the ninth. Determine the ninth value.
    A 72 Correct Answer Incorrect Answer
    B 65 Correct Answer Incorrect Answer
    C 88 Correct Answer Incorrect Answer
    D 55 Correct Answer Incorrect Answer

    Solution

    Let ninth number is x Eighth number = 0.25x Tenth number = 1.75x According to question; x + 0.25x + 1.75x = 15 × 72 – 7 × 62 – 5 × 86 = 216 Or, 3x = 216 Or, x = 72

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