And as you can see, X can take on only a finite number of values, zero, one, two, three, or four, and so because there's a finite number of values here, we would call this a discrete random variable. And you can see that this is a valid probability distribution because the combined probability is one. .1 plus 0.15 plus 0.4 plus 0.25 plus 0.1 is one, and none of these are negative probabilities, which wouldn't have made sense. But what we care about in this video is the notion of an expected value of a discrete random variable, which you would just note this way. And one way to think about it is, once we calculate the expected value of this variable, of this random variable, that in a given week, that would give you a sense of the expected number of workouts. This is also sometimes referred to as the mean of a random variable. This right over here is the Greek letter mu, which is often used to denote the mean, so this is the mean of the random variable X.