IXL | Interpret measures of center and variability

Scarlett learned how to measure pH using a science kit she got as a gift. Using small strips of special paper, she tested the pH of the water at school, at her home, and in 6 brands of bottled water. The measurements ranged from a pH of 6.5 to 8.25. The mean pH was about 7.4, and the mean absolute deviation was 0.5.

Which number best describes a typical pH of the water Scarlett tested?

0.5

6.5

7.4

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Learn with an example

question

Barbara works in an electronics store. The store sells 7 different brands and models of tablets. All of the tablets have screen sizes of less than 11 inches, and most are less than 10 inches. The median screen size is 9.4 inches, and the interquartile range is about 2.1 inches.

Which is a measure of how much these tablets' screen sizes vary?

2.1 inches

9.4 inches

10 inches

11 inches

key idea

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. It describes the variability of the data set.

solution

You want to describe how much these tablets' screen sizes vary.

Use the interquartile range, since it describes the variability of the data set. The IQR is about 2.1 inches.

So, these tablets' screen sizes vary by about 2.1

inches.

Looking for more? Try these:

Lesson: Mean, median, mode, and range

Lesson: Interquartile range

Lesson: Mean absolute deviation

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Teacher tools

Work it out

Not feeling ready yet? These can help:

JJ.2Calculate mean, median, mode, and range

JJ.6Calculate mean absolute deviation

JJ.7Calculate quartiles and interquartile range

Lesson: Mean, median, mode, and range

Lesson: Interquartile range

Lesson: Mean absolute deviation

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