So you take the square root of the variance, you get the standard deviation. That's why I got rid of that to the second power. And you want to take a square root of the right-hand side, just like that. Now, all I did right now is just to kind of conceptually set things up in our brain. What we now need to do is actually tackle the confidence interval. We actually need to come up with a 95% confidence interval for P1 minus P2, or a 95% confidence interval for this mean right over here. And because I'm trying to make my best effort not to make videos too long, I'll do part two in the next video where we actually solve the confidence interval.