Lesson 9-6

Type of Area	Acreage	
Battlefield Site	1	
Historic Sites	37,557	
Historical Parks	167,208	
Lakeshores	228,847	
Memorials	8,532	
Reserves	33,431	
Rivers	424,630	
Scenic Trails	233,608	
Seashores	594,854	
Parkways	174,917	
Example 1 Construct a Box-and-Whisker Plot
NATIONAL PARKS Use the data in the table to construct a box-and-whisker plot.

Step 1	Draw a number line that includes the least and greatest number in the data.

Step 2	Mark the extremes, the median, and the upper and lower quartile above the number line. Since the data have an outlier, mark the least value that is not an outlier.

Step 3	Draw the box and whiskers.

Source: www2.nature.nps.gov

Example 2 Interpret Data
FOOD What does the length of the box-and-whisker plot below tell you about the data?

The median line seems to divide the box into two approximately equal parts, so data in the second and third quartiles are similarly spread out. The whisker at the left is longer than the other parts of the plot, so the data in the first quartile are more spread out.

Example 3 Compare Data
CAMP Refer to the double box-and-whisker plot below. Were about half the men and women in the same age group? Justify your reasoning.

The youngest age of the men was 21.5 years, and the median was 26 years. So half of the men were 21.5 to 26 years old.

The median age of the women was 22 years, and the oldest age was 25. So half of the women were 22 to 25 years old.

So, about half the men and women were in the same age group.