The interquartile range is the range from the 1st quartile to the 3rd quartile...
First order the elements from least to greatest...
42, 45, 48, 50, 50, 60, 65, 80
The median is 50 so the first quartile is 48 and the third quartile is 60.
So the interquartile range is Q3-Q1=60-48=12
