Answer:
21.08
Explanation:
Mean = {Sum of the terms} ÷ {the number of terms}
5 terms 28, 21.8,21.1,19, and 15.5.
Add those which is your sum.
28+21.8+21.1+19+15.5=105.4
So what you do is what i said above which is {Sum of the terms} ÷ {the number of terms}
So.....
105.4 ÷ 5 = 21.08 and that is the answer.