Embed Size (px)
Citation preview
Frequency Tables, Stem-and-Leaf Plots, and Line Plots
*Notes 50
VocabularyFrequency table- a way to organize data
into categories or groups.
Cumulative frequency- a running total of the frequencies in each category.
Stem-and-leaf plot- uses the digits of each number to organize and display a set of data. Each leaf on the plot represents the right-hand digit in a data value, and each stem represents the reamining left-hand digits.
Line plot- display of a set of data where each separate piece of data is shown as a dot or mark above a number line.
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.
The frequency of a data value is the number of times it occurs.
Remember!
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
Additional Example 1: Organizing and Interpreting Data in a Frequency Table
February Temperatures in 20 CitiesAverage
HighsFrequency Cumulative
FrequencyStep 1: Choose a scale that includes all of the data values. Then separate the scale into equal intervals.
0–19
20–39
40–59
60–79
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
Additional Example 1 Continued
Step 2: Find the number of data values in each interval. Write these numbers in the “Frequency” column.
February Temperatures in 20 CitiesAverage
HighsFrequency Cumulative
Frequency
7
5
5
3
0–19
20–39
40–59
60–79
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
Additional Example 1 Continued
Step 3: Find the cumulative frequency for each row by adding all the frequency values that are above or in that row.
February Temperatures in 20 CitiesAverage
HighsFrequency Cumulative
Frequency
0–19
20–39
40–59
60–79
7
5
5
3
7
12
17
20
17 cities had average high temperature below 59 degrees.
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
A stem-and-leaf plot uses the digits of each number to organize and display a set of data. Each leaf on the plot represents the right-hand digit in a data value, and each stem represents the remaining left-hand digits.
2 4 7 9
3 0 6
Stems Leaves
Key: 2|7 means 27
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
Additional Example 2: Organizing and Interpreting Data in a Stem-and-Leaf Plot
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.
Additional Example 2 Continued
Step 2: List the stems from least to greatest on the plot.
Stems Leaves
1
2
3
4
The stems are the tens digits.
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
Additional Example 2 Continued
Step 3: List the leaves for each stem from least to greatest.
Stems Leaves
1
2
3
4
The stems are the tens digits.
2 5 5 7 7 8
0 1 2 3 3 93 3
0
The leaves are the ones digits.
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
Additional Example 2 Continued
Step 4: Add a key and a title.
The stems are the tens digits.
Stems Leaves
1
2
3
4
2 5 5 7 7 8
0 1 2 3 3 93 3
0
The leaves are the ones digits.
Number of Years Coached
Key: 2 | 1 means 21.
11 coaches coached fewer than 25 years.
The table shows the number of points a playerscored during the last ten games of the season.Make a stem-and-leaf plot of the data. In howmany games did the player score less than 30points?
Check It Out: Example 2
42
Mar 4
46Feb 20
43Mar 127Feb 18
31Feb 2734Feb 14
18Feb 2536Feb 7
PointsPoints
32 28Feb 23
Mar 3
GameDate GameDate
Make a line plot of the data. How many hours per day did Morgan babysit most often?
Additional Example 3: Organizing and Interpreting Data in a Line Plot
0633484Wk 4
2165860Wk 3
8607772Wk 2
2856460Wk 1
SuSFThWTM
Number of Babysitting Hours in July
Make a line plot of the data. How many hours per day did Morgan babysit most often?
Additional Example 3 Continued
Step 1: The data values range from 0 to 8. Draw a number line that includes this range.
0 1 2 3 4 5 6 7 8
Make a line plot of the data. How many hours per day did Morgan babysit most often?
Additional Example 3 Continued
Step 1: The data values range from 0 to 8. Draw a number line that includes this range.
0 1 2 3 4 5 6 7 8
Make a line plot of the data. How many hours per day did Morgan babysit most often?
Additional Example 3 Continued
Step 2: Put an X above the number on the number line that corresponds to the number of babysitting hours in July.
0 1 2 3 4 5 6 7 8
XXXX X
XXX
XX
XXX
XX
XXXXXX
XXX
XXXX
The greatest number of X’s appear above the number 6. This means that Morgan babysat most often for 6 hours.
Check It Out: Example 3
The hourly rates Morgan got for her last 10 jobs were $6, $6, $8, $7, $8, $9, $6,$10, $8, $6. Make a line plot of the data. What was the most common hourly rate?
