And that needs to be the case, because these are the only two possibilities that can occur. If this is 60% chance of success, there has to be a 40% chance of failure. 70% chance of success, 30% chance of failure. Now, with this definition of this, and this is the most general definition of a Bernoulli distribution, it's really exactly what we did in the last video. I now want to calculate the expected value, which is the same thing as the mean of this distribution. And I also want to calculate the variance, which is the same thing as the expected squared distance of a value from the mean. So let's do that.