So that's 20 plus 30 is 50, plus 30 is 80. This is the total column right over here. And then the total people that didn't get sick over here is 100 plus 110 is 210, plus 90 is 300. And then the total people here are 380. Both this column and this row should add up to 380. So with that out of the way, let's think about how we can use this information in the contingency table and our knowledge of the chi-squared distribution to come up with some conclusion. So let's just make a null hypothesis.