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The Standard Deviation :: Standard Deviation Calculation Short-Cut Method
This method might be a bit faster to calculate. Calculate the Standard Deviation for the following data using the calculator to the right (round to 1 decimal points). Click on the Check Answer button to see how you did.

Data: 2, 7, 8, 9, 12, 16, 18     Load another set of data

1Add up all the values.
Sum
72
2Square this sum
Sum Squared
5184
3Count the total number of values.
n
7
4Divide Sum Squared by the the total number of values
Avg. Sum Squared
740.57
5Square each individual value. 
622 4
772 49
882 64
992 81
10122 144
11162 256
12182 324
13Add up all these squared values.
Sum of Squares
922
14Subtract Sum of Squares - Avg. Sum Squared 181.43
15Divide this by the total number of values minus 1.
sample variance
30.24
16Take the square root of the variance.
sample standard deviation
5.5

Check Answers

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