6th Grade Math Textbook, Progress

Box-and-Whisker Plots

9-7

Use the box-and-whisker plot above.

1. How many quartiles or values 2. Which characteristic of a box-and-
   are needed to divide the data into whisker plot can be used to
   four parts? determine the range of the data?


2. About how much of the data are 4. If each score was tripled, how
   in the box? would the shape of the box change?

The data set shows student scores from a 120-point reading test.

A box-and-whisker plot can be used to show the data distribution.

A box-and-whisker plot includes a number line that shows

the extremes (greatest and least) numbers, the median, and

the quartile divisions. A box is drawn on top of the second

and third quartiles. The whiskers show the first and fourth quartiles.

To make a box-and-whisker plot:


Order the data from least to

greatest.

Find the median. Then find

the upperand lowerquartiles,

which are the middle values

of each half of the data.

Display the extremes, quartiles,

and median as points above

a number line.

Draw a boxthat ends at the

lower and upper quartiles.

Then draw a vertical line segment

through the box at the median.

Draw horizontal line segments,

called whiskers, from the ends

of the box to the lower and

upper extremes.

Write a title for the plot.

50 60 80

100 90 70

70 110 90

Scores

50, 60, 70, 70, 80, 9 0, 9 0, 100, 110

40 50 60 70 80 90 100 110 120

lower

extreme

lower

extreme

lower

quartile

lower

quartile

median

median

before median

upper

quartile

upper

quartile

upper

extreme

upper

extreme

after median

90 
 100

2

60
(^70)  95
2
 65
40 50 60 70 80 90 100 110 120
whisker box whisker
Reading Test Scores
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