Printer-friendly version. Expected Value (i.e., Mean) of a Discrete Random Variable. Law of Large Numbers: Given a large number of repeated trials, the average. In probability and statistics, the expectation or expected value, is the weighted average value of a random variable. In this video, I show the formula of expected value, and compute the expected value of a game. The final. You may need to use a sample space The sample space for this problem is: Expected value is exactly what you might think it means intuitively: What is Expected Value? The way that this seems to be is that you need to know how to set up your tables with the information given to you. Multiply your X values in Step 1 by the probabilities from step 2.