Question

What is the interquartile range (IQR) for the data set?

14, 15, 17, 19, 20, 23, 26, 30, 32
Group of answer choices

12

16

20

28

Answer 1

First find Q1 and Q3. With 9 values the median is the 5th value = 20, so lower half is 14,15,17,19 and upper half is 23,26,30,32.
Q1 = median of lower half = (15+17)/2 = 16.
Q3 = median of upper half = (26+30)/2 = 28.
IQR = Q3 − Q1 = 28 − 16 = 12.