First, you arrange the number in order from least to greatest.
6, 13, 15, 19, 19, 20, 25, 26, 31, 38, 41
You then find the median. (number in the middle). Which is, 20.
Now you put the numbers to the side of 20 in parenthesis.
(6, 13, 15, 19, 19) 20 ( 25, 26, 31, 38, 41)
Now you find the median of the numbers in parenthesis. Which are, 15 and 31.
Now subtract the number on the left from the right.
31-15=16
The interquartile range (IQR) is 16.
