Compare Measures of Variation Practice

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Question
Here are the science test scores from Ms. O’Donnell’s class:

55, 60, 70, 70, 75, 75, 75, 80, 80, 85, 85, 85, 85, 90, 90, 95, 100

Find the MAD.

1 answer

To find the MAD (Mean Absolute Deviation) of the test scores, follow these steps:

1. Find the mean of the data set:
Mean = (55 + 60 + 70 + 70 + 75 + 75 + 75 + 80 + 80 + 85 + 85 + 85 + 85 + 90 + 90 + 95 + 100) / 17 = 79.41

2. Find the absolute deviation of each score from the mean:
|55 - 79.41| = 24.41
|60 - 79.41| = 19.41
|70 - 79.41| = 9.41
|75 - 79.41| = 4.41
|80 - 79.41| = 0.59
|85 - 79.41| = 5.59
|90 - 79.41| = 10.59
|95 - 79.41| = 15.59
|100 - 79.41| = 20.59

3. Find the mean of the absolute deviations:
MAD = (24.41 + 19.41 + 9.41 + 4.41 + 0.59 + 5.59 + 10.59 + 15.59 + 20.59) / 9 ≈ 11.76

Therefore, the Mean Absolute Deviation (MAD) of the test scores is approximately 11.76.