Question 5 • Concepts in Probability and Statistics A
The data are already in order, and the median is 25. The lower half is 15, 19, 20, so its median is Q1 = 19; the upper half is 31, 38, 41, so its median is Q3 = 38. The interquartile range is Q3 − Q1 = 38 − 19 = 19, so the answer is 19 (choice C).
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