In the last video, we figured out the mean, variance, and standard deviation for a Bernoulli distribution with specific numbers. What I want to do in this video is to generalize it, to figure out really the formulas for the mean and the variance of a Bernoulli distribution if we don't have the actual numbers. If we just know that the probability of success is p, and the probability of failure is 1 minus p. So let's look at this. Let's look at a population where the probability of success, and we'll define success as 1, as having a probability of p. And the probability of failure is 1 minus p, whatever this might be. And obviously, if you add these two up, if you view them as percentages, these are going to add up to 100%. Or if you add up these two values, you're going to add to 1. And that needs to be the case, because these are the only two possibilities that can occur.