### 9.2 Describing "Average"

• Math Help

A box-and-whisker plot highlights some of the important features of a data set. To graph a box-and-whisker plot, you must know the following values.

• The minimum value
• The lower (or first) quartile
• The median (or second quartile)
• The upper (or third) quartile
• The maximum value

The three quartiles divide an ordered data set into approximately four equal parts. About one quarter of the data fall on or below the first quartile. About one half of the data fall on or below the second quartile (the median). About three quarters of the data fall on or below the third quartile. Here is an example of three quartiles dividing an ordered data set into approximately four equal parts. You can also use the Box-and-Whisker Plot Generator located in Tools to make box-and-whisker plots.

• Consumer Suggestion

If you've been considering starting an exercise program you might want to check out this article from menshealth.com, which describes a typical training regimen for the NFL combine.

• Checkpoint Solution

Here are some other observations that you can make about the weights of the players.

• About 10 of the players weigh between 170 and 188.75 pounds.
• About 10 of the players weigh between 188.75 and 200 pounds.
• About 10 of the players weigh between 200 and 215 pounds.
• About 10 of the players weigh between 215 and 240 pounds.
• There is not a very large difference between the ranges of weights for the quartiles. The greatest range is 25 pounds and the smallest range is 10 pounds. The weights are clustered much closer to the mean for the Los Angeles Angels than they are for the Chicago Bears.

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