Question 477210: Help! The process?
Find the sample mean, variance, and standard deviation. (For standard deviation, round answer to two decimal places.)
−9, −5, −4, −1, 0, 1
sample mean = -3
sample variance = ?
sample standard deviation = ?
Answer by jim_thompson5910(35256)   (Show Source):
You can put this solution on YOUR website!
Finding the sample standard deviation:
First, subtract the sample mean from EVERY data value:
-9-(-3) = -6
-5-(-3) = -2
-4-(-3) = -1
-1-(-3) = 2
0-(-3) = 3
1-(-3) = 4
So the differences are: -6, -2, -1, 2, 3, 4
Now square each difference:
(-6)^2 = 36
(-2)^2 = 4
(-1)^2 = 1
(2)^2 = 4
(3)^2 = 9
(4)^2 = 16
Now add up each square:
36+4+1+4+9+16 = 70
Now divide that sum by n-1 = 6-1 = 5 to get 70/5 = 14
This value (14) is known as the sample variance.
Finally, take the square root of 14 to get 3.74165738677394 and round to two places to get 3.74
So the sample standard deviation is 3.74
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