2-3 Line Plots
DAP 1- Read, create, & interpret graphs when appropriate
DAP 3- Analyze a set of data by using & comparing
combinations of measures of central tendancy
Pages 64-67
One type of graph is a line plot. They
are usually used when there is one
group of data, and fewer than 50
values.
Benefits of Using Line Plots:
• Line Plots can be used to show how
data is spread out.
• A line plot provides an easy way to
organize data.
• A line plot shows the frequency of
data on a number line .
Parts of a Line Plot
• A horizontal number line
• An “X” is placed above a
number on the # line each time
that the value occurs
• The number of “X's” above
each value indicates how many
times (the frequency) each
value occurred
Make a Line Plot
Suppose thirty people live in an apartment building.
They are the following ages:
Ages of People Living in the
apartment building
Step 1: place the values in
order from least to
greatest
30, 34, 34, 35, 35, 35, 36, 37, 38,
39, 40, 40, 40, 46, 46, 47, 47, 47,
47, 47, 47, 48, 48, 48, 49, 49, 50,
54, 54, 58
Step 2: create your graph
58
30
37
36
34
49
35
40
47
47
39
54
47
48
54
50
35
40
38
47
48
34
40
46
49
47
35
48
47
46
This graph shows all the ages of the people
who live in the apartment building.
How old is the youngest person in the apartment building?
30
How old is the oldest person?
58
What is the most common age of the residents in the building?
47
Line plots allow several features of the data to
become more obvious. For example,
outliers, clusters, and gaps are apparent.
Outliers are data points whose values are
significantly larger or smaller than other
values, such as the ages of 30, and 58.
Clusters are isolated groups of points, such as
the ages of 46 through 50.
Gaps are large spaces between points, such
as 41 and 45.
The range of the data is the difference
between the greatest and least numbers in
the data set, such as 58-30= 28.
You Try…
Age at Inauguration
The table at the right shows the
ages of the U.S. Presidents at the
time of their inaugurations.
57 51 54 56 61 61
49 49 55 52 57 64
Make a line plot of the data.
50 51 69 57 50 47
What is the youngest entry on the
data table?
54 64 58 48 55 51
What is the eldest entry on the
data table?
61 52 54 62 68 54
Let’s start at 40 and finish at 75.
56
40
45
50
55
46 57 65 55 60 54
56 42 43 46
60
65
Identify any clusters, gaps and outliers that exist.
What is the range of the given data?
70
51 55
75