Variance of x bar minus y bar. Now, what are these in terms of the original population distribution? Well, we came up with those results right over here. 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.