Multiple choice

What is the mean deviation of the mean of the first nine multiples of 3?

  1. 3.24

  2. 5.42

  3. 6.67

  4. 7.55

  5. NA
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C Correct answer
Explanation

First nine multiples of 3: 3, 6, 9, 12, 15, 18, 21, 24, 27. Mean = 135 / 9 = 15. Mean deviation = (|3-15| + |6-15| + |9-15| + |12-15| + |15-15| + |18-15| + |21-15| + |24-15| + |27-15|) / 9 = (12+9+6+3+0+3+6+9+12) / 9 = 60 / 9 = 6.67.

AI explanation

The first nine multiples of 3 are 3, 6, 9, 12, 15, 18, 21, 24 and 27. Their mean is 135 divided by 9, which is 15. The absolute deviations from 15 are 12, 9, 6, 3, 0, 3, 6, 9 and 12, which sum to 60. The mean deviation is 60 divided by 9, giving 6.67.

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