43 times 1 divided by 100 is 0.43. That is my sample mean, the mean of just the 100 data points that I actually got. Now, what is my sample variance? Is going to be equal to the sum of my squared distances to the mean divided by my samples minus 1. Remember, this is a sample variance. And we want to get the best estimator of the real variance of this distribution. And to do that, you don't divide by 100.