EXAMPLE 1

1. EXAMPLE 1 Making a Stem-and-Leaf Plot Speeds of Animals The table lists the maximum running speeds of various animals. How can the data be displayed to show the distribution of the speeds?

2. EXAMPLE 1 Making a Stem-and-Leaf Plot Speeds of Animals A stem-and-leaf plot is a data display that helps you to see the way data are distributed. You can use a stem-and-leaf plot to place data in increasing order.

3. EXAMPLE 1 Making a Stem-and-Leaf Plot Display the speeds of the animals in a stem-and-leaf plot. SOLUTION Choose the stems and leaves. The numbers range from 32 to 70, so let the stems be the tens’ digits from 3 to 7. Let the leaves be the ones’ digits. STEP 1 STEP 2 Write the stems first. Draw a vertical line segment next to the stems. Then record each speed by writing its ones’ digit on the same line as its corresponding tens’ digit.

4. 2 9 34567 9 2 34567 0 3 5 7 5 7 0 3 0 0 0 0 Key: 4 7= 47 Key: 4 7 = 47 EXAMPLE 1 Making a Stem-and-Leaf Plot STEP 3 Make an ordered stem-and-leaf plot. Include a key to show what the stems and leaves represent. Ordered Plot Unordered Plot

5. 89.490 87.5 84.3 89.7 90.3 91.1 91 86 84.1 89.2 86 89.1 88.2 89.5 85.6 90.5 90.2 91.1 88.9 EXAMPLE 2 Interpreting a Stem-and-Leaf Plot Bicycle Stunt Competition The point totals (rounded to the nearest tenth) for the 20 participants in a bicycle stunt competition are listed below. The rider with the greatest point total out of 100 points wins. Use a stem-and-leaf plot to order the data. Make a conclusion about the data.

6. EXAMPLE 2 Interpreting a Stem-and-Leaf Plot SOLUTION Begin by making an unordered stem-and-leaf plot. Because the point totals range from 84.1 to 91.4, the stems are the digits in the tens’ and ones’ places. The leaves are the digits in the tenths’ place.

7. Unordered Plot Ordered Plot 8485868788899091 8485868788899091 3 1 1 3 6 6 0 0 0 0 5 5 2 9 2 9 4 7 2 1 5 1 2 4 5 7 0 3 5 2 0 2 3 5 1 0 1 0 1 1 Key: 87 5 = 87.5 Key: 87 5 = 87.5 EXAMPLE 2 Interpreting a Stem-and-Leaf Plot SOLUTION Then make an ordered stem-and-leaf plot.

8. ANSWER More than half of the participants finished near the top of the range, with 12 of the 20 participants having point totals greater than or equal to 89. EXAMPLE 2 Interpreting a Stem-and-Leaf Plot

9. The test scores for the students in a social studies class are listed below. Make an ordered stem-and-leaf plot of the scores. 1. GUIDED PRACTICE for Examples 1 and 2 Test Scores 92 78 73 89 98 89 83 75 83 100 69 71 96 67 81 73 88 86 82 94

10. GUIDED PRACTICE for Examples 1 and 2 ANSWER

11. ANSWER ANSWER 9 7 GUIDED PRACTICE for Examples 1 and 2 Use the stem-and-leaf plot from Exercise 1 to answer the questions. 2. How many test scores are greater than 84? 3. How many test scores are less than80?

12. ANSWER 3 modes; 73, 83, and 89 Many scores fell in the 80’s, with two more scoresbelow 80 than 90 or above. Most scores were above 70. ANSWER ANSWER 83 GUIDED PRACTICE for Examples 1 and 2 Use the stem-and-leaf plot from Exercise 1 to answer the questions. 4. Identify the median of the data?. 5. How many modes do the data have? What are they? 6. Make a conclusion about the test scores.