**Variance & Std. Deviation**

Average of squared deviations from mean. Population variance:

Sample variance:

Standard deviation:Â

Â

**Chebyshev's Inequality**

% of observations lying within k-standard deviations of the mean >= 1-1/k2

**Practice Question:**

Calculate the standard deviation of following data set:

Data Set A: 10,20,30,40,50

Data Set B: 10,20,70,120,130

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