11-3
Box-and-Whisker Plots
Warm Up
1. Order the test scores from least to
greatest: 89, 93, 79, 87, 91, 88, 92.
79, 87, 88, 89, 91, 92, 93
2. Find the median of the test scores.
89
Find the difference.
3. 17 – 0.9 16.1
4. 8.4 – 7. 6 0.8
5. 9.1 – 5.7 3.4
6. 190.3 – 23.4 166.9
Holt CA Course 1
11-3
Box-and-Whisker Plots
Common Core State Standards
Learning Objective
7.SP.3
Compare two numerical data
distributions.
Holt CA Course 1
11-3
Box-and-Whisker Plots
Vocabulary
lower quartile
upper quartile
box-and-whisker plot
minimum
maximum
Holt CA Course 1
11-3
Box-and-Whisker Plots
The table below summarizes a cat breeder’s
records for kitten litters born in a given year. You
can divide the data into four equal part using
quartiles.
Litter Size
2
3
4
5
6
Number of
Litters
1
6
8
11
1
Holt CA Course 1
11-3
Box-and-Whisker Plots
You know that the median of a data set divides the
data into a lower half and an upper half. The median
of the lower half is the lower quartile, and the
median of the upper half is the upper quartile.
Kitten Data
Lower half
Upper half
233333344444444555555555556
Upper quartile: 5
Lower quartile: 3
median of upper half
median of lower half
Median: 4
Holt CA Course 1
11-3
Box-and-Whisker Plots
Additional Example 1: Finding Quartiles
Find the lower and upper quartiles for the data
set.
A. 15, 83, 75, 12, 19, 74, 21
12 15 19 21 74 75 83
lower quartile: 15
upper quartile: 75
Holt CA Course 1
Order the values.
11-3
Box-and-Whisker Plots
Additional Example 1: Finding Quartiles
Find the lower and upper quartiles for the data
set.
B. 75, 61, 88, 79, 79, 99, 63, 77
61 63 75 77 79 79 88 99
lower quartile:
Order the values.
63 + 75
= 69
2
79 + 88
upper quartile:
= 83.5
2
Holt CA Course 1
11-3
Box-and-Whisker Plots
Check It Out! Example 1
Find the lower and upper quartiles for the data
set.
A. 25, 38, 66, 19, 91, 47, 13
13 19 25 38 47 66 91
lower quartile: 19
upper quartile: 66
Holt CA Course 1
Order the values.
11-3
Box-and-Whisker Plots
Check It Out! Example 1
Find the lower and upper quartiles for the data
set.
B. 45, 31, 59, 49, 49, 69, 33, 47
31 33 45 47 49 49 59 69
Order the values.
33 + 45
lower quartile:
= 39
2
49 + 59
upper quartile:
= 54
2
Holt CA Course 1
11-3
Box-and-Whisker Plots
A box-and-whisker plot shows the
distribution of data. The middle half of the
data is represented by a “box” with a vertical
line at the median. The lower fourth and
upper fourth quarters are represented by
“whiskers” that extend to the minimum
(least) and maximum (greatest) values.
1
2
3
Lower quartile
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4
Median
5
6
7
8
Upper quartile
9
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Box-and-Whisker Plots
Additional Example 2: Making a Box-and-Whisker Plot
Use the given data to make a box-and-whisker plot.
21, 25, 15, 13, 17, 19, 19, 21
Step 1. Order the data from least to greatest. Then
find the minimum, lower quartile, median, upper
quartile, and maximum.
13 15 17 19 19 21 21 25
minimum: 13
15 + 17
lower quartile:
2
maximum: 25
= 16 upper quartile:
median:
Holt CA Course 1
19 + 19
2
= 19
21 + 21
2
= 21
11-3
Box-and-Whisker Plots
Additional Example 2 Continued
Use the given data to make a box-and-whisker plot.
Step 2. Draw a number line and plot a point above
each value from Step 1.
13 15 17 19 19 21 21 25
12
Holt CA Course 1
14
16
18
20
22
24
26 28
11-3
Box-and-Whisker Plots
Additional Example 2 Continued
Use the given data to make a box-and-whisker plot.
Step 3. Draw the box and whiskers.
13 15 17 19 19 21 21 25
12
Holt CA Course 1
14
16
18
20
22
24
26 28
11-3
Box-and-Whisker Plots
Check It Out! Example 2
Use the given data to make a box-and-whisker plot.
31, 23, 33, 35, 26, 24, 31, 29
Step 1. Order the data from least to greatest. Then
find the minimum, lower quartile, median, upper
quartile, and maximum.
23 24 26 29 31 31 33 35
minimum: 23
lower quartile:
maximum: 35
24 + 26
2
= 25 upper quartile:
median: 29 + 31 = 30
2
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31 + 33
2
= 32
11-3
Box-and-Whisker Plots
Check It Out! Example 2 Continued
Use the given data to make a box-and-whisker plot.
Step 2. Draw a number line and plot a point above
each value.
23 24 26 29 31 31 33 35
22
Holt CA Course 1
24
26
28
30
32
34
36 38
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Box-and-Whisker Plots
Check It Out! Example 2 Continued
Use the given data to make a box-and-whisker plot.
Step 2.
3. Draw a
the
box and
whiskers.
number
line
and plot a point above
each value.
23 24 26 29 31 31 33 35
22
Holt CA Course 1
24
26
28
30
32
34
36 38
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Box-and-Whisker Plots
Check It Out! Example 3
These box-and-whisker
plots compare the
points per quarter at
Super Bowl XXXVII.
0
Quarter
1
2
3
4
Oakland
3
0
6
12
Tampa Bay
3
17
14
14
Oakland
3
6
9
12
15
18
Tampa Bay
0
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3
6
9
12
15
18
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Box-and-Whisker Plots
Check It Out! Example 3A
A. Compare the medians.
The median for
Tampa Bay is
significantly
greater than
Oakland’s.
Oakland
0
3
6
9
12
15
18
Tampa Bay
0
Holt CA Course 1
3
6
9
12
15
18
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Box-and-Whisker Plots
Lesson Quiz: Part I
Find the lower and upper quartiles for each
data set.
1. 48, 52, 68, 32, 53, 47, 51
lower = 47; upper = 53
2. 3, 18, 11, 2, 7, 5, 9, 6, 13, 1, 17, 8, 0
lower = 2.5; upper = 12
Holt CA Course 1
11-3
Box-and-Whisker Plots
Lesson Quiz: Part II
Use the following data for problems 3 and 4.
91, 87, 98, 93, 89, 78, 94
3. Make a box-and-whisker plot.
78
87
91
4. What is the median of the data?
91
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94
98
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Box-and-Whisker Plots
Checking for Understanding
Box and Whisker Plots
Holt CA Course 1
11-3
Box-and-Whisker Plots
Classwork & Homework
Lesson 11-3 Practice B
Lesson 11-3 Problem Solving
Holt CA Course 1