Mean, Median, Mode and Range

Lesson 2-6 and 2-7

Mean

• The mean of a set of data is the average.

• Add up all of the data.• Divide the sum by the number of

data items you have.

Example: Find the mean.

4, 16, 20, 40

First, add. 4 + 16 + 20 + 40 = 80

There are 4 items. Divide the sum (80) by 4.

The mean is 20.

Outliers• Outliers are values and are MUCH

higher or lower than the other numbers in the data set– If the outlier is bigger it makes the

mean higher than most of the data set.

– If the outlier is smaller it makes the mean smaller than the numbers in the data set.* Without outliers, the mean is better represented*

Median

• The median is the data point that is in the middle when the data is listed in order from LEAST TO GREATEST

• If there are two numbers in the middle (an even number of items), then find the mean of the two middle numbers.

Examples: Find the median.

13, 16, 17, 19, 2517 is the median.

3, 5, 6, 9Here, the 5 and 6 are both in the middle. 5 + 6 = 11. 11 divided by 2 = 5.5. The median is 5.5.

19, 17, 25, 13, 16

Example: Find the mode.

5, 4, 6, 11, 5, 7, 10, 5The mode is 5.

11, 24, 2, 69, 11, 9, 9The mode is 11 and 9.

Mode

• The mode is the data item that appears the most. (there can be more than 1 mode)

• If all data items appear only once, then there is no mode.

Range

• The range of a set of data is the difference between the greatest and the least values.

Ex) 65, 68, 72, 65, 80, 55, 65Range: 80 – 55 = 25

Find the Median, Mode and Range or the data.

Number of Calories in Selected Vegetables (per serving)

15 35 50

31 5 25

85 25 20

55 15 40

Median: 28Mode: 15 and 25Range: 80