NAME _____________________________________________ DATE ____________________________ PERIOD _____________
Skills Practice 11.4
Mean Absolute Deviation
Find the mean absolute deviation for each set of data. Round to the nearest hundredth if necessary.
1. Mean Absolute Deviation_____________
2. Mean Absolute Deviation_____________
Number of Sunny Days in
Various Cities Last Month
Cost of Video Games ($)
40
55
60
48
57
33
57
20
80
47
27
15
10
19
24
21
28
16
For Exercise 3–6, refer to the table that shows the
highway fuel economy of various popular vehicles.
3. Find the mean absolute deviation. Round to the
nearest hundredth.
Fuel Economy
(Miles per Gallon)
34
48
25
35
33
37
32
34
23
30
4. How many data values are closer than one mean absolute
deviation away from the mean?
5. Which data value is farthest from the mean? How far is this
value from the mean? Round to the nearest hundredth.
6. Are there any data values that are more than twice the
mean absolute deviation from the mean? Explain.
Course 1 • Chapter 11 Statistical Measures
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NAME _____________________________________________ DATE ____________________________ PERIOD _____________
Study Guide 11.4
Mean Absolute Deviation
• absolute value: The distance between a number and zero on a number line. |–5| = 5
• mean absolute deviation: A measure of variation in a set of numerical data, computed by adding the distances
between each data value and the mean, then dividing the number of data values.
Example
Project Work Hours
The table shows the number of hours each
member of the study group spent working on
the class project. Find the mean absolute
deviation of the set of data. Describe what the
mean absolute deviation represents.
Step 1 Find the mean.
3 + 8 + 11 + 5 + 9 + 6 + 10 + 4
8
3
8
11
5
9
6
10
4
=7
Step 2 Find the absolute value of the differences between
each value in the data set and the mean.
Each data value is represented by an X.
Step 3 Find the average of the absolute values of the differences between each value in the data set and the mean.
4+3+2+1+1+2+3+4
= 2.5
8
The mean absolute deviation is 2.5. This means that the data values are an average distance of 2.5 hours from the mean.
How many data values are closer than one mean absolute deviation away from the mean?
To find this, subtract the MAD from the mean and add the MAD to the mean.
7.0 mean
-2.5 MAD
4.5
7.0 mean
+2.5 MAD
9.5
The values of 5, 6, 8 and 9 are with one mean absolute deviation from the mean. There are 4 values closer than one mean
absolute deviation from the mean.
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