But in the null hypothesis, we are going to assume that p1 is equal to p2. That's what we do. We assume the null hypothesis and see the probability of this occurring. So if p1 is equal to p2, we can just represent them as just some true population proportion. So we could say that this is going to be equal to, so we could write it like this. The square root of, we can literally just factor out, 1 over 1,000 times p times 1 minus p plus p times 1 minus p, because they're going to be the same value. That's what we're assuming in the null hypothesis.