The mean of a set of data values is the sum of all of the data values divided by the number of data values.
[tex]\overline{x}=\dfrac{4+4+5+4+4+5+5+5+4}{9}=\dfrac{40}{9}\approx4.4[/tex]
The median of a set of data values is the middle value of the data set when it has been arranged in ascending order.
[tex]4,\ 4,\ 4,\ 4,\ \boxed{4},\ 5,\ 5,\ 5,\ 5\\\\Median=4[/tex]
The mode of a set of data values is the value(s) that occurs most often.
[tex]\underbrace{4,\ 4,\ 4,\ 4,\ 4}_{5},\underbrace{5,\ 5,\ 5,\ 5}_{4}\\\\Mode=4[/tex]
The range of a set of data is the difference between the highest and lowest values in the set.
[tex]5-4=1\\\\Range=1[/tex]