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

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 dа ta: 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

I believe the answer is 57.