The expected value is known as the "long-term" average or mean. This means that over the long term of experimenting over and over, you would expect this average. The expected average is represented by the symbol μ. It is calculated as follows:

In the equation, x is an event, and P(x) is the probability of the event occurring.

The expected value has practical applications in decision theory.

This text is adapted from Openstax, Introductory Statistics, Section 4.2 Mean or Expected Value and Standard Deviation.