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Variance

Definition of Variance

• Variance is a statistical measure that tells us how measured data vary from the average value of the set of data.
• In other words, variance is the mean of the squares of the deviations from the arithmetic mean of a data set.

More about Variance

• Variance is the square of the standard deviation.
• The formula for variance is

Solved Example on Variance

Find the variance of the data set {1, 2, 3, 4, 10}. 
Choices:
A. 10
B.  9
C.  8
D.  7
Correct answer: A
Solution:
Step 1:  The mean of the data set {1, 2, 3, 4, 10} is .      [Use the formula for mean.]                         
Step 2: The standard deviation of the data set is
                [Use the formula for mean.]       
Step 3:  
Step 4: The variance of the data set is .  [Substitute .] 

Related Terms for Variance

• Arithmetic Mean
• Standard Deviation