This is the sampling distribution of this statistic, of P1 minus P2. And so it has some mean over here. It has some mean, the mean of the sample of P1 minus the sample mean, or the sample proportion of P2. And we know from things that we've done in the last several videos, that this is going to be the exact same thing as this mean minus this mean, which is the exact same thing as P1 minus P2. So this is going to be equal to P1 minus P2. And the variance of this distribution, so the variance of this distribution, P1 minus P2, just like this, is going to be the sum of the variances of these two distributions. So it's going to be this thing over here.