What you’ll learn to do: understand and calculate the standard deviation of a discrete random variable

Although a family may have 0, 1, 2, 3 or more children, we often want to know how many children are in a family on average. Reporting that a family has 2.1 children may sound strange, but this is the long-term average based on selecting many families and not the number of children in an individual family. In this section, you will learn how to find the mean (or average) and standard deviation for a discrete random variable.