1-6 Box-and-Whisker Plots
Learn to display and analyze data in
box-and-whisker plots.
Course 2
1-6 Box-and-Whisker Plots
Vocabulary
box-and-whisker plot
lower quartile
upper quartile
median
minimum extreme
maximum extreme
Course 2
1-6 Box-and-Whisker Plots
The table shows the stopping distances of
different vehicles from 60 mi/h.
Vehicle
Stopping
Distance (ft)
A
120
B
158
C
142
D
131
E
128
F
167
G
136
To show the distribution of the data, you
can use a box-and-whisker plot.
Course 2
1-6 Box-and-Whisker Plots
To make a box-and-whisker plot for a set of
data, you need to divide the data into four
equal parts using quartiles.
The following box-and-whisker plot shows
the distribution of the vehicles’ stopping
distances.
Course 2
1-6 Box-and-Whisker Plots
Lower Quartile, the
median of the lower
half of the data set
Minimum
Extreme, or
minimum value
110
Course 2
120
Upper Quartile, the
median of the upper
half of the data set
Median, the median of
the data set
130
140
150
160
Maximum
Extreme, or
maximum value
170
180
1-6 Box-and-Whisker Plots
Additional Example 1: Reading a Box-and-Whisker Plot
Use the box-and-whisker plot of students enrolled in
craft classes to answer each question.
10
11 12
13 14
15 16 17
18
19 20
21 22 23 24
25 26
A. What is the largest class size?
The largest data value is represented by the maximum on
the box-and whisker plot. This value is 25.
B. What is the range of the class sizes?
The range is the difference between the minimum extreme
and the maximum extreme : 25 – 10 = 15.
C. About what fraction of the values are greater than 20?
One of the four parts of the box-and-whisker plot falls
above 20. This means about one-fourth of the values are
greater than 20.
Course 2
1-6 Box-and-Whisker Plots
Try This: Example 1
Use the box-and-whisker plot of the amount of money
spent on a pair of shoes to answer each question.
26
27
28 29 30 31
32 33
34
35 36 37 38
39
40 41
A. What was the highest amount of money spent on a
pair of shoes? 41
B. What is the range of shoe prices?
The range is the difference between the lower extreme
and the upper extreme: 41 – 27 = 14.
1
C. What fraction of shoes cost more than $35?
2
Course 2
1-6 Box-and-Whisker Plots
Additional Example 2: Making a Box-and-Whisker Plot
Use the data to make a box-and-whisker plot.
73 67 75 81 67 75 85 69 Step 1: Find the lower and upper extremes, the median, and
the first and third quartiles.
Order the data from least
67 67 69 73 75 75 81 85
to greatest.
67 67 69 73 75 75 81 85
Find the lower and upper
extremes.
67 67 69 73+75 75 81 85
2
=74
Find the median.
Course 2
1-6 Box-and-Whisker Plots
Additional Example 2 Continued
67 67 69 73 75 75 81 85
first quartile =
third quartile =
Course 2
67 + 69 = 68
2
75 + 81
= 78
2
Find the first and
third quartiles.
1-6 Box-and-Whisker Plots
Additional Example 2 Continued
Step 2: Draw a number line.
Above the number line, plot points
representing the lower and upper extremes,
the median, and the first and third quartiles.
Step 3: Draw a box through the first and third quartiles.
Inside the box, draw a vertical line through the median.
Then draw lines from the first and third quartiles to
the extremes. These lines are called whiskers.
64
Course 2
66
68
70
72
74
76
78
80
82
84
86
1-6 Box-and-Whisker Plots
Try This: Example 2
Use the data to make a box-and-whisker plot.
42 22 31 27 24 38 35
Step 1: Find the lower and upper extremes, the median, and
the first and third quartiles.
Order the data from least
22 24 27 31 35 38 42
to greatest.
22 24 27 31 35 38 42
Find the lower and upper
extremes.
22 24 27 31 35 38 42
Find the median.
22 24 27 31 35 38 42
Find the first and third
quartiles.
Course 2
1-6 Box-and-Whisker Plots
Try This: Example 2 Continued
Step 2: Draw a number line.
Above the number line, plot points
representing the lower and upper extremes,
the median, and the first and third quartiles.
Step 3: Draw a box through the first and third quartiles.
Inside the box, draw a vertical line through the median.
Then draw lines from the first and third quartiles to
the extremes. These lines are called whiskers.
20
Course 2
22
24
26
28
30
32
34
36
38
40
42
1-6 Box-and-Whisker Plots
Lesson Quiz
Use the data for Questions 1-3.
24, 20, 18, 25, 22, 32, 30, 29, 35, 30, 28, 24, 38
1. What is the range? 20
2. What is the 3rd quartile? 31
3. Create a box-and-whisker plot for the data.
18
Course 2
20
22
24
26
28
30
32
34
36
38
40