A box plot (five-number summary) represents the distribution of times (in minutes) to complete a puzzle for a group of students: minimum 5, , median 10, , maximum 30. What is the interquartile range (IQR), and what is the range?
- IQR 6; range 22
- IQR 6; range 25 (correct answer)
- IQR 9; range 22
- IQR 9; range 25
Explanation: The question asks for the interquartile range (IQR) and range from a box plot with minimum 5, Q1=8, median 10, Q3=14, maximum 30. The IQR is Q3 minus Q1, so 14 - 8 = 6, representing the spread of the middle 50% of times. The range is maximum minus minimum, or 30 - 5 = 25, showing the full spread including outliers. These measures highlight different aspects: IQR resists extremes, while range includes them. A key error is subtracting median instead of Q1 from Q3 for IQR. When reading box plots, note that IQR focuses on central spread, making it useful for comparing distributions; verify by direct subtraction.