Answer:
Step-by-step explanation:
3,9,12,(15),16,18,21
mean (middle number) = 15
Q1 = 9.....the middle number of the numbers before the mean
Q3 = 18...the middle number of the numbers after the mean
interquartile range (IQR) = Q3 - Q1 = 18 - 9 = 9 <==
