Question

in the data set below, what is the interquartile range? 2 4 4 7 9

Explanation:

Step1: Arrange data in order

2, 4, 4, 7, 9

Step2: Find median (Q2)

Since there are 5 data - points, the median is the 3rd value. So Q2 = 4.

Step3: Find lower half

The lower half is 2, 4. The median of the lower half (Q1) is $\frac{2 + 4}{2}=3$.

Step4: Find upper half

The upper half is 7, 9. The median of the upper half (Q3) is $\frac{7+9}{2}=8$.

Step5: Calculate inter - quartile range

IQR = Q3 - Q1 = 8 - 3 = 5.

Answer:

5