Binomial Mean and Variance

Notes:

• The sums given above define the mean and variance of a binomial distribution. Note that besides working with these sums to obtain the final expressions given above for the mean and variance, there are other simpler approaches to obtain these expressions. Usually, such derivations are outside the scope of an introductory course.
• Take the square root of the variance to obtain the standard deviation of the binomial distribution. You need to know the mean and standard deviation of the binomial distribution when you undertake a normal approximation to the binomial.