Answer: choice D) 2.5
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Step-by-step explanation:
Original set = {12, 11, 6, 10, 5, 13, 6, 9}
n = 8 is the number of values in that set above
Add up the values 12+11+6+10+5+13+6+9 = 72
Divide that sum by n = 8 to get 72/8 = 9. So the mean = 9
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For each value in the original set {12, 11, 6, 10, 5, 13, 6, 9} subtract off the mean = 9. Apply the absolute value to ensure the result is positive or zero
|x - mean| = |12 - 9| = 3
|x - mean| = |11 - 9| = 2
|x - mean| = |6 - 9| = 3
|x - mean| = |10 - 9| = 1
|x - mean| = |5 - 9| = 4
|x - mean| = |13 - 9| = 4
|x - mean| = |6 - 9| = 3
|x - mean| = |9 - 9| = 0
The set of results we get are: {3, 2, 3, 1, 4, 4, 3, 0} which adds up to 3+2+3+1+4+4+3+0 = 20, then we divide that over n = 8 to get 20/8 = 2.5
Therefore the mean absolute deviation (MAD) is 2.5