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    Question

    The mean of 5 observations is 10 and their standard

    deviation is 4. Each observation is multiplied by 3 and then increased by 5. Find the new mean and the new standard deviation.
    A 33 Correct Answer Incorrect Answer
    B 12 Correct Answer Incorrect Answer
    C 21 Correct Answer Incorrect Answer
    D 18 Correct Answer Incorrect Answer

    Solution

    ATQ, If each observation is multiplied by a and then increased by b: New mean = a × (old mean) + b New standard deviation = |a| × (old SD) Here a = 3, b = 5. New mean = 3 × 10 + 5 = 35 New SD = 3 × 4 = 12

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