1. 6-9 Stem-and-Leaf Plots Warm Up Problem of the Day Lesson Presentation
Course 1
Warm Up
Problem of the Day
Lesson Presentation

2. Warm Up
A set of data ranges from 12 to 86. What intervals would you use to display this data in a histogram with four intervals?
Possible answer: 10–29, 30–49, 50–69, 70–89

3. Problem of the Day
What is the least number that can be divided evenly by each of the numbers 1 through 12?
27,720

4. Learn to make and analyze stem-and-leaf plots.

5. Vocabulary
stem-and-leaf plot

6. A stem-and-leaf plot shows data arranged by place value
A stem-and-leaf plot shows data arranged by place value. You can use a stem-and-leaf plot when you want to display data in an organized way that allows you to see each value.

7. Additional Example 1: Creating Stem-and-Leaf Plots
Use the data in the table to make a stem-and-leaf plot.
Test Scores 75 86 83 91 94 88 84 99 79
Step 1: Group the data by tens digits.
75 79
Step 2: Order the data from least to greatest.

8. Helpful Hint
To write 42 in a stem-and-leaf plot, write each digit in a separate column.
4 2
Stem
Leaf

9. Additional Example 1 Continued
Step 3: List the tens digits of the data in order from least to greatest. Write these in the “stems” column.
75 79
Step 4: For each tens digit, record the ones digits of each data value in order from least to greatest. Write these in the “leaves” column.
Test Scores
Stems
Leaves
Step 5: Title the graph and add a key. 7
5 9 8 9
Key: 7 5 means 75

10. Use the data in the table to make a stem-and-leaf plot. Test Scores 72
Check It Out: Example 1
Use the data in the table to make a stem-and-leaf plot.
Test Scores 72 88 64 79 61 84 83 76 74 67
Step 1: Group the data by tens digits.
Step 2: Order the data from least to greatest.

11. Check It Out: Example 1 Continued
Step 3: List the tens digits of the data in order from least to greatest. Write these in the “stems” column.
Step 4: For each tens digit, record the ones digits of each data value in order from least to greatest. Write these in the “leaves” column.
Test Scores
Stems
Leaves
Step 5: Title the graph and add a key. 6 7 8
Key: 6 1 means 61

12. Additional Example 2: Reading Stem-and-Leaf Plots
Find the least value, greatest value, mean, median, mode, and range of the data.
The least stem and least leaf give the least value, 40.
Stems
Leaves 4
The greatest stem and greatest leaf give the greatest value, 94. 5 6 7
0 4 4 8
3 6 7
Use the data values to find the mean (40 + … + 94) ÷ 23 = 64. 9
1 4
Key: 4 0 means 40

13. Additional Example 2 Continued
The median is the middle value in the table, 63.
To find the mode, look for the number that occurs most often in a row of leaves. Then identify its stem. The mode is 63.
Stems
Leaves 4 5 6 7
0 4 4
The range is the difference between the greatest and the least value. 94 – 40 = 54. 8
3 6 7 9
1 4
Key: 4 0 means 40

14. The least stem and least leaf give the least value, 30. Stems Leaves 3
Check It Out: Example 2
Find the least value, greatest value, mean, median, mode, and range of the data.
The least stem and least leaf give the least value, 30.
Stems
Leaves 3
The greatest stem and greatest leaf give the greatest value, 85. 4 5 6
1 2 4
Use the data values to find the mean (30 + … + 85) ÷ 23 = 55. 7
5 6 9 8
1 5
Key: 3 0 means 30

15. Check It Out: Example 2 Continued
The median is the middle value in the table, 56.
To find the mode, look for the number that occurs most often in a row of leaves. Then identify its stem. The mode is 59.
Stems
Leaves 3 4 5 6
1 2 4
The range is the difference between the greatest and the least value. 85 – 30 = 55. 7
5 6 9 8
1 5
Key: 3 0 means 30

16. 1. Make a stem-and-leaf plot of the data.
Lesson Quiz: Part I
1. Make a stem-and-leaf plot of the data.
5 2
Stems
Leaves
Key: 3 | 0 means 30

17. Lesson Quiz: Part II
Find each value using the stem-and-leaf plot.
2. What is the least value?
3. What is the mean?
4. What is the median?
5. What is the mode? 21
34.75 34 34