We know what the standard deviation. We know that this thing is the same thing as the variance of the population distribution divided by n. We've done this multiple, multiple times. So this is going to be equal to, what's this going to be equal to? This part right here is the same thing as the variance of our population distribution. And the x just means this is for random variable x. But there's no bar on top. This is the actual population distribution, not the sampling distribution of the sample mean.