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6-9. Stem-and-Leaf Plots. 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
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6-9 Stem-and-Leaf Plots 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
Vocabulary stem-and-leaf plot
A stem-and-leaf plotshows 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. 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 Leaf Stem
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
Check It Out: Example 1 Use the data in the table to make a stem-and-leaf plot. 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. 1 1 2 4 5 3 3 3 5 9 9 6 0 4 4 7 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 1 1 2 4 5 3 3 3 5 9 9 6 0 4 4 7 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
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 0 2 5 6 8 3 The greatest stem and greatest leaf give the greatest value, 85. 1 1 3 4 4 4 5 6 9 9 9 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
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 0 2 5 6 8 3 1 1 3 4 4 4 5 6 9 9 9 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
Stems Leaves 2 1 2 7 8 9 3 0 1 4 4 5 6 4 0 2 6 9 5 2 Key: 3 | 0 means 30 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
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