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

Transcription

1 7.1 Frequency Tables, Stem-n-Leaf Plots, and Line Plots Learn to organize and interpret data in frequency tables and stem-and-leaf plots, and line plots. Vocabulary A frequency table is a way to organize data into categories or groups. By including a cumulative frequency column in your table, you can keep a running total of the frequencies in each category.

2 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 Step 1: Choose a scale that includes all of the data values. Then separate the scale into equal intervals.

3 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 Step 2: Find the number of data values in each interval. Write these numbers in the Frequency column.

4 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 Step 3: Find the cumulative frequency for each row by adding all the frequency values that are above or in that row. How many cities had average high temperature below 59 degrees?

5 Check It Out: Example 1 The list shows the grades received on an English exam. Make a cumulative frequency table of the data. How many students received a grade of 79 or below? 85, 84, 77, 65, 99, 90, 80, 85, 95, 72, 60, 66, 94, 86, 79, 87, 68, 95, 71, 96 Step 1: Choose a scale that includes all of the data values. Then separate the scale into equal intervals. Step 2: Find the number of data values in each interval. Write these numbers in the Frequency column. Step 3: Find the cumulative frequency for each row by adding all the frequency values that are above or in that row. How many students received a grade of 79 or below?

6 Vocabulary A stem-and-leaf plot can be used to show how often data values occur and how they are distributed. Each leaf on the plot represents the right-hand digit in a data value, and each stem represents left-hand digits.

7 Example 2: Organizing and Interpreting Data in a Stem-and-Leaf Plot 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 1: Order the data from least to greatest. Since the data values range from 12 to 40, use tens digits for the stems and ones digits for the leaves.

8 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.

9 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. The number of coaches who coached fewer than 25 years is

10 Check It Out: Example 2 The list shows the number of times each soccer player can bounce the ball on their knee. How many soccer players can bounce the ball more than 36 times. 55, 60, 33, 30, 23, 45, 28, 41, 62, 29, 35, 40, 43, 37, 68, 30, 61, 27, 38, 41 Step 1: Order the data from least to greatest Step 2: List the stems from least to greatest on the plot. Step 3: List the leaves for each stem from least to greatest. How many soccer players can bounce the ball more than 36 times?

11 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? Step 1: The data values range from 0 to 8. Draw a number line that includes this range.

12 Step 1: The data values range from 0 to 8. Draw a number line that includes this range. Step 2: Put an X above the number on the number line that corresponds to the number of babysitting hours in July. The greatest number of X s appear above the number. This means that Morgan babysat most often for hours.

13 Check It Out: Example 3 Make a line plot of the data. How many slices of pizza did most people eat? Step 1: The data values range from 0 to 6. Draw a number line that includes this range. Step 2: Put an X above the number on the number line that corresponds to the number slices of pizza eaten per person. The greatest number of X s appear above the number. This means that most people ate slices of pizza.

14 Lesson Quiz: Part I The data shows the ages of some hospital nurses. 33, 35, 23, 39, 23, 24, 34, 21, 57, 45, 57, 60, 45, 24, 31, 42, 61, 45, 35, Make a cumulative frequency table of the data. How many of the nurses are under the age of 40?

15 Lesson Quiz: Part II The data shows the ages of some hospital nurses. 33, 35, 23, 39, 23, 24, 34, 21, 57, 45, 57, 60, 45, 24, 31, 42, 61, 45, 35, Make a stem-and-leaf plot of the data. How many nurses are over the age of 45?

16 Lesson Quiz: Part III The data shows the ages of some hospital nurses. 33, 35, 23, 39, 23, 24, 34, 21, 57, 45, 57, 60, 45, 24, 31, 42, 61, 45, 35, Make a line plot of the data. What age occurs most often?