What is Stefano's error?

Stefano should have divided by 5 when finding the mean.

Stefano found the absolute deviation of 20 incorrectly.

Stefano should have divided by 6 when finding the mean absolute deviation.

Stefano did not find the correct value for the mean.

Your data is missing, but I have answered this question previously.

To find the mean, you add all the numbers together and then divide by the number of numbers (6).

4 + 12 + 20 + 24 + 32 + 40 = 132132/6 = 22

To find the mean absolute deviation, you will find the distance between each number and the mean and then divide this by 6 as well.

(22-4) + (22-12) + (22-20) + (24-22) + (32-22) + (40-22) 18 + 10 + 2 + 2 + 10 + 18 = 6060/6 = 10

The mean absolute deviation is 10.

The correct answer is that Stefano should have divided by 6 when finding the mean absolute deviation.