Find the population standard deviation (σ not s) for the data set: {75,80,90,95,75,85,55,80,90,95}
round your answer to the nearest 10th.

1. Find the mean (arithmetic mean) of the numbers:



2. Find the differences of each number to the mean, and calculate the square of each of these differences :

82-75=7,           7^2=49
82-80=2            2^2=4
90-82=8            8^2=64
95-82=13         13^2=169
82-75=7            7^2=49
85-82=3             3^2=9
82-55=27           27^2=729
82-80=2              2^2=4
90-82=8             8^2=64
95-82=13           13^2=169

3. Calculate the mean of the differences (the Variance):



4. Standart deviation is the root of the variance = 

D.