Frequency Tables, Stem-and-Leaf
7-1 Plots, and Line Plots
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.
Remember!
The frequency of a data value is the
number of times it occurs.
Frequency Tables, Stem-and-Leaf
7-1 Plots, and Line Plots
Additional Example 1 Continued
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.
February Temperatures in 20 Cities
Average
Frequency Cumulative
Frequency
Highs
0–19
20–39
40–59
7
5
5
12
17
60–79
3
20
7
17 cities had average high temperature below 59 degrees.
Frequency Tables, Stem-and-Leaf
7-1 Plots, and Line Plots
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
Frequency Tables, Stem-and-Leaf
7-1 Plots, and Line Plots
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 reamining left-hand
digits.
Stems
2
3
Leaves
4 7 9
0 6
Key: 2|7 means 27
Frequency Tables, Stem-and-Leaf
7-1 Plots, and Line Plots
Additional Example 2 Continued
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
Stems
Leaves
Frequency Tables, Stem-and-Leaf
7-1 Plots, and Line Plots
Check It Out: Example 2
The table shows the number of points a player
scored during the last ten games of the season.
Make a stem-and-leaf plot of the data. In how
many games did the player score less than 30
points?
GameDate
Points GameDate Points
Feb 7
36
Feb 25
18
Feb 14
34
Feb 27
31
Feb 18
27
Mar 1
43
Feb 20
46
Mar 3
42
Feb 23
32
Mar 4
28
Frequency Tables, Stem-and-Leaf
7-1 Plots, and Line Plots
Additional 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?
Number of Babysitting Hours in July
M
T
W
Th
F
S
Su
Wk 1
0
6
4
6
5
8
2
Wk 2
2
7
7
7
0
6
8
Wk 3
0
6
8
5
6
1
2
Wk 4
4
8
4
3
3
6
0