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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, 3, 9, 10, 11, 13, 18     Load another set of data

1Add up all the values.
Sum
66
2Square this sum
Sum Squared
4356
3Count the total number of values.
n
7
4Divide Sum Squared by the the total number of values
Avg. Sum Squared
622.29
5Square each individual value. 
622 4
732 9
892 81
9102 100
10112 121
11132 169
12182 324
13Add up all these squared values.
Sum of Squares
808
14Subtract Sum of Squares - Avg. Sum Squared 185.71
15Divide this by the total number of values minus 1.
sample variance
30.95
16Take the square root of the variance.
sample standard deviation
5.56

Check Answers

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