Exercise 2 Page 497

We want to find the interquartile range of the given data set. 15, 7, 5, 8, 9, 20, 12, 7, 11, 7, 15 To do this we need to identify the quartiles.

• Second Quartile (Q_2) is the median of the data set. It divides the set of data into two halves.
• Lower Quartile (Q_1) is the median of the lower half of the data set.
• Upper Quartile (Q_3) is the median of the upper half of the data set.
• Interquartile Range is the difference between the upper quartile and the lower quartile (Q_3-Q_1).

Let's start by ordering the data set from least to greatest value! 5, 7, 7, 7, 8, 9, 11, 12, 15, 15, 20 The number of values in our data set is 11. This is why sixth value in order, 9 is the median of the set. This value divides the set into two halves. We have one middle value for each half. These are the quartiles. Upper Quartile:& 15 Lower Quartile:& 7 The last step to calculate the interquartile range is to calculate the difference between the upper and the lower quartile. Let's do it! Interquartile Range:& 15- 7= 8 We found that the interquartile range for the given data is 8. This corresponds to answer F.