1. Warm Up 1. 2. Identify the least and greatest value in each set.
34, 62, 45, 35, 75, 23, 35, 65
23, 75
1.6, 3.4, 2.6, 4.8, 1.3, 3.5, 4.0
1.3, 4.8

2. Objectives Describe the central tendency of a data set.
Create and interpret box-and-whisker plots.

3. A measure of central tendency describes the center of a set of data
A measure of central tendency describes the center of a set of data. Measures of central tendency include the mean, median, and mode.
The mean is the average of the data values, or the sum of the values in the set divided by the number of values in the set.
The median the middle value when the values are in numerical order, or the mean of the two middle numbers if there are an even number of values.

4. The mode is the value or values that occur most often
The mode is the value or values that occur most often. A data set may have one mode or more than one mode. If no value occurs more often than another, we say the data set has no mode.
The range of a set of data is the difference between the least and greatest values in the set. The range describes the spread of the data.

5. Additional Example 1: Finding Mean, Median, Mode, and Range of a Data Set
The weights in pounds of six members of a basketball team are 161, 156, 150, 156, 150, and 163. Find the mean, median, mode, and range of the data set.
Write the data in numerical order.
Add all the values and divide by the number of values.
mean:
median: 150, 150, 156, 156, 161, 163
The median is 156.
There are an even number of values. Find the mean of the two middle values.

6. Additional Example 1 Continued
150, 150, 156, 156, 161, 163
modes: 150 and 156
150 and 156 both occur more often than any other value.
range: 163 – 150 = 13

7. Example 2
The weights in pounds of five cats are 12, 14, 12, 16, and 16. Find the mean, median, mode, and range of the data set.
12, 12, 14, 16, 16
Write the data in numerical order.
Add all the values and divide by the number of values.
median: 12, 12, 14, 16, 16
The median is 14.
There are an odd number of values. Find the middle value.

8. Example 2 Continued
The weights in pounds of five cats are 12, 14, 12, 16, and 16.Find the mean, median, mode, and range of the data set.
mode: 12 and 16
The data set is bi-modal as 12 and 14 both occur twice.
range: 12 – 16 = 4

9. Additional Example 3: Choosing a Measure of Central Tendency
Rico scored 74, 73, 80, 75, 67, and 54 on six history tests. Use the mean, median, and mode of his scores to answer each question.
mean ≈ median = mode = none
A. Which measure best describes Rico’s scores?
Median: 73.5; the outlier of 54 lowers the mean, and there is no mode.
B. Which measure should Rico use to describe his test scores to his parents? Explain.
Median: 73.5; the median is greater than the mean, and there is no mode.

10. Example 4
Josh scored 75, 75, 81, 84, and 85 on five tests. Use the mean, median, and mode of his scores to answer each question.
mean = median = 81 mode = 75
a. Which measure describes the score Josh received most often?
Josh has two scores of 75 which is the mode.
b. Which measure best describes Josh’s scores? Explain.
Median: 81; the median is greater than either the mean or the mode.

11. Mean, Median, Mode Worksheet Due: September 9th
HOMEWORK
Mean, Median, Mode Worksheet Due: September 9th