1. Learn to organize and interpret data in frequency tables, stem-and-leaf plots, and line plots.

2. Additional Example 1: Organizing and Interpreting Data in a Frequency Table
The list shows the average high temperatures for 20 cities on one February day. Make a cumulative frequency table of the data. How many cities had average high temperature below 59 degrees?
69, 66, 65, 51, 50, 50, 44, 41, 38, 32, 32, 28, 20, 18, 12, 8, 8, 4, 2, 2
February Temperatures in 20 Cities
Average Highs
Frequency
Cumulative Frequency
Step 1: Look at the range to choose equal intervals for the data.
0–20
21-40
41-60
61-80

3. Additional Example 1 Continued
The list shows the average high temperatures for 20 cities on one February day. Make a cumulative frequency table of the data. How many cities had average high temperature below 59 degrees?
69, 66, 65, 51, 50, 50, 44, 41, 38, 32, 32, 28, 20, 18, 12, 8, 8, 4, 2, 2
February Temperatures in 20 Cities
Average Highs
Frequency
Cumulative Frequency
Step 2: Find the number of data values in each interval. Write these numbers in the “Frequency” column.
0–20 8
21-40 4
41-60 5
61-80 3

4. Additional Example 1 Continued
The list shows the average high temperatures for 20 cities on one February day. Make a cumulative frequency table of the data. How many cities had average high temperature below 59 degrees?
69, 66, 65, 51, 50, 50, 44, 41, 38, 32, 32, 28, 20, 18, 12, 8, 8, 4, 2, 2
February Temperatures in 20 Cities
Average Highs
Frequency
Cumulative Frequency
0–20
21-40
41–60
61-80 8 4 5 3
Step 3: Find the cumulative frequency for each row by adding all the frequency values that are above or in that row. 8 12 17 20
17 cities had average high temperature below 59 degrees.

5. Stem and Leaf Plots
The data shows the number of years coached by the top 15 coaches in the all-time NFL coaching victories. Make a stem-and-leaf plot of the data. Then find the number of coaches who coached fewer than 25 years.
33, 40, 29, 33, 21, 23, 23, 22, 19, 21, 18, 23, 15, 15, 15
Step 1: Find the least data value and the greatest data value. Since the data values range from 15 to 40, use tends digits for stems and ones digits for the leaves.

6. Additional Example 2 Continued
The data shows the number of years coached by the top 15 coaches in the all-time NFL coaching victories. Make a stem-and-leaf plot of the data. Then find the number of coaches who coached fewer than 25 years.
33, 40, 29, 33, 23, 22, 20, 21, 18, 23, 17, 15, 15, 12, 17
Step 2: List the stems from least to greatest on the plot.
Stems Leaves
The stems are the tens digits. 1 2 3 4

7. Additional Example 2 Continued
The data shows the number of years coached by the top 15 coaches in the all-time NFL coaching victories. Make a stem-and-leaf plot of the data. Then find the number of coaches who coached fewer than 25 years.
33, 40, 29, 33, 23, 22, 20, 21, 18, 23, 17, 15, 15, 12, 17
Step 3: List the leaves for each stem from least to greatest.
Stems Leaves
The stems are the tens digits.
The leaves are the ones digits. 5 5 5 8 9 1 2 3 4 1 1 2 3 3 3 9 3 3

8. Additional Example 2 Continued
Step 4: Add a key and a title The stems area the tens digits. The leaves are the ones digits.
Number of Years Coached
The stems are the tens digits.
The leaves are the ones digits.
Key: 2 | 1 means 21.
11 coaches coached fewer than 25 years.

9. Additional Example 3: Organizing and Interpreting Data in a Line Plot
Make a line plot of the data. How many hours per day did Morgan babysit most often?
Number of Babysitting Hours in July 6 3 4 8
Wk 4 2 1 5
Wk 3 7
Wk 2
Wk 1 Su S F Th W T M

10. Additional Example 3 Continued
Make a line plot of the data. How many hours per day did Morgan babysit most often?
Step 1: The data values range from 0 to 8. Draw a number line that includes this range.

11. Additional Example 3 Continued
Make a line plot of the data. How many hours per day did Morgan babysit most often?
Step 2: Put an X above the number on the number line that corresponds to the number of hours Morgan babysat each day.
XX XX XX
XX XX
XX XX
XX X
XX X
XX X XX XX X
The greatest number of X’s appear above the number 6. This means that Morgan babysat most often for 6 hours.