Variance of a Random Variable

Summary

the standard deviation or variance of a probability distribution is a measure of the spread of likely values of a random variable.

the variance of the discrete random variable x with e(x) = μ is given by:

var(x) = e(x − μ)= e(x2) − [e(x)]2

Key Skills

calculate the variance of a probability distribution given a table of probabilities using both versions of the formula.

Vocabulary

variance, probability distributionspreadrandom variablestandard deviation.