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

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

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

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

Vocabulary stem-and-leaf plot

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.

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 83 84 86 86 88 Step 2: Order the data from least to greatest. 91 94 99

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

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 83 84 86 86 88 91 94 99 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 3 4 6 6 8 9 1 4 9 Key: 7 5 means 75

Use the data in the table to make a stem-and-leaf plot. Test Scores 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. 61 64 67 72 74 76 79 Step 2: Order the data from least to greatest. 83 84 88

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. 61 64 67 72 74 76 79 83 84 88 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 1 4 7 7 2 4 6 9 8 3 4 8 Key: 6 1 means 61

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 0 0 1 5 7 The greatest stem and greatest leaf give the greatest value, 94. 5 1 1 2 4 6 3 3 3 5 9 9 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

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 0 0 1 5 7 5 1 1 2 4 6 3 3 3 5 9 9 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

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 0 2 5 6 8 The greatest stem and greatest leaf give the greatest value, 85. 4 1 1 3 4 5 4 5 6 9 9 9 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

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 0 2 5 6 8 4 1 1 3 4 5 4 5 6 9 9 9 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

1. Make a stem-and-leaf plot of the data. Lesson Quiz: Part I 1. Make a stem-and-leaf plot of the data. 42 36 40 31 29 49 21 28 52 27 22 35 30 46 34 34 2 1 2 7 8 9 3 0 1 4 4 5 6 4 0 2 6 9 5 2 Stems Leaves Key: 3 | 0 means 30

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