Unit 8, Lesson 15

Quartiles and Interquartile Range

Grade 6

Practice

Problem 1

Suppose that there are 20 numbers in a data set and that they are all different.

How many of the values in this data set are between the first quartile and the third quartile?
How many of the values in this data set are between the first quartile and the median?

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Problem 2

In a word game, 1 letter is worth 1 point. This dot plot shows the scores for 20 common words.

<p>A dot plot, word value in points, 0 to 22 by twos. Beginning at 4 in increments of 1, the number of dots above each increment is 4, 2, 4, 3, 3, 3. There is a dot above 22.</p><br>

What is the median score?
What is the first quartile (Q1)?
What is the third quartile (Q3)?
What is the interquartile range (IQR)?

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Problem 3

Mai and Priya each bowl 10 games and record the scores. Mai’s median score is 120, and her IQR is 5. Priya’s median score is 118, and her IQR is 15. Whose scores probably have less variability? Explain how you know.

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Problem 4

Here are five dot plots that show the amounts of time that ten sixth-grade students in five countries took to get to school. Match each dot plot with the appropriate median and IQR.