And so this, sorry, the standard deviation of these distributions, and to make, so you don't get confused between that and that, and let me say the variance. If you know the variance, you can figure out the standard deviation. One is just the square root of the other. So this is the variance of our original distribution. Now, to show that this is the variance of our sampling distribution of our sample mean, we'll write it right here. This is the variance of our mean, of our sample mean. Remember, the sample, our true mean is this, that the Greek letter mu is your true mean.