Question

What is the interquartile range of 56, 78, 124, 34, 67, 91, 20

Answer 1

The interquartile range, IQR, is the difference between the third interquartile, Q3, and the first interquartile, Q1.

This is: IQR = Q3 - Q1.

The first interquartile is the 25% percentile and the third interquartile is the 75% percentile.

Order the data: 20, 34, 56, 67, 78, 91, 124.

In those data the median is 67

The first interquartile, Q1 is the median of the values from 20 to 67, which is (34 + 56) / 2 = 45.

The third interquartile, Q3, is the median from 67 to 124 =  (78 + 91) / 2 = 84.5

IQR = 84.5 - 45 = 39.5

Answer: 39.5

Answer 2

I believe the answer is 57.