Answer:
Median = 18
This is the middle line in the box.
Range = 6
This is the difference between the highest and lowest values, 21 - 15.
25th percentile = 17
This is the Q1 value, which is the left side of the box.
75th percentile = 20
This is the Q3 value, which is the right side of the box.
Interquartile range = 3
This is Q3-Q1, which is 20 - 17. This is another way to measure spread.
