Box-and-whisker plots & Dot Plots

How to read a box-and-whisker plot.• Dots outside of the box

and whiskers are outliers.• Maximum and minimum

values are shown at the ends of each whisker.

• The upper and lower quartiles are the ends of the box.

• The median is the line in the middle of the box.

Outlier

Minimum

Lower quartile

Median

Upper quartile

Maximum

Outlier

Example 1• Ruby asked the students in her class how long their

families spent making dinner each night. This box-and-whisker plot shows the results.

Find the following values:Minimum: LQ: Maximum: UQ:Range: Interquartile Range: Median:

20 25 50 45

30 20 35

Practice Problem 1

• A professor asked her students to keep track of how many websites they visit each day. This box-and-whisker plot shows the results.

Find the following values:Minimum: LQ: Maximum: UQ:Range: Interquartile Range: Median:

4 5 10 8

6 3 7

How to read dot plots

• The dots above each number represent a number in the data set.

• If dots are stacked on top of each other, that means that the value occurs more than once.

• Labeling the axis is key to determining the numbers in the data set.

Example 2• From the dot plot below, you can see that there

are few values near the maximum and minimum values.

• There are clusters of values between 64 and 80. • You can infer that for this dot plot, most

people’s pulses were between 64bpm and 80 bpm.

Comparing two dot plots• The dotplots to the right show pet

ownership in two city blocks. • As seen in the graph, pet

ownership in block a is lower.– In block a, the amount of pets that people

own ranges between 0 and 4.

• In block b, most households have two or more pets. – In block b, the amount of pet ranges

between 0 and 6.

Practice Problem

• The dot plot below shows the age of actors and actresses who win awards. Make a prediction about the ages of actresses and actors in the dot plots below.

Actresses win more awards than actors at a younger age. Actors win more awards than actresses at an older age.