IXL | Compare populations using box plots

Shawna surveyed a sample of 15 beginner musicians and 15 advanced musicians, asking how long they practice each day. The results are recorded in the box plots.

Practice time (minutes)

Beginner

Advanced

110

Complete the table.

	Median	Interquartile range
Beginner		20
Advanced	60

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Learn with an example

question

Reba found a box of baseball cards in her grandparents' attic. She looked up the value of a sample of 10 baseball cards from the 1920s and 10 baseball cards from the 1990s. The results are recorded in the box plots.

Value (dollars)

1920s

1990s

100

300

500

700

900

1,100

Complete the table.

	Median	Interquartile range
1920s	$ 700	$
1990s	$	$ 200

key idea

A box plot shows the minimum, lower quartile, median, upper quartile, and maximum of a data set.

The median is the middle value when a data set is ordered from least to greatest. It describes the center of the data set.

The interquartile range (IQR) is the range of the middle 50% of the data set, which is the difference between the upper quartile and the lower quartile. It describes the variability of the data set.

solution

First, find the interquartile range of the value for the sample of 1920s cards. Subtract the lower quartile from the upper quartile.

Value (dollars)

1920s

1990s

100

300

400

500

700

900

1,100

The interquartile range for the sample of 1920s cards is

900

–

400

500

Next, find the median value for the sample of 1990s cards.

Value (dollars)

1920s

1990s

100

300

500

700

900

1,100

The median for the sample of 1990s cards is

300

Finally, use these values to complete the table.

	Median	Interquartile range
1920s	$ 700	$ 500
1990s	$ 300	$ 200

$Confetti$

Excellent!

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