Answer:
2.6
Explanation:
The Mean Absolute Deviation (MAD) is the average amount that each point is from the overall average of the data set.
So, first find the overall average (also called the mean):
avg = (1 + 1 + 2 + 3 + 5 + 7 + 9) / 7
= 28 / 7
= 4
The average (mean) is 4, so now you calculate how far each point is from 4 and average those numbers:
Note: Remember to use absolute values, since distance can't be negative.
4 - 1 = 3
4 - 1 = 3
4 - 2 = 2
4 - 3 = 1
4 - 5 = |-1| = 1
4 - 7 = |-3| = 3
4 - 9 = |-5| = 5
And finally, average (or find the mean) the new data set:
avg = (1 + 1 + 2 + 3 + 3 + 3 + 5) / 7
so 18 / 7 is the MAD of the data set.
Finally, round it to the nearest tenth:
18 ÷ 7 = 2.57142857143 ≈ 2.6