 Hi, we're going to do an example on how to build a confidence interval for a population proportion. Out of 300 people sampled, 45 had kids. To instruct a 99% confidence interval for the true population proportion of people with kids, give your answers as decimals to three places. So P is my population proportion. To find the confidence interval predicting this value, I have to take my point estimate or sample proportion and add the margin of error to it and then take my point estimate or sample proportion and subtract the margin of error from it. So we'll first calculate this by hand and then we'll actually use technology to make our life a little bit easier. First, we'll start off with the sample proportion, P hat. That is the number of people that have kids. Well, there's 45 out of 300. 45 out of 300 gives you a sample proportion of about point 15. Next, let's talk about our error bound formula. The formula for error bound is E equals the critical value Z sub alpha over two times the square root of P hat times Q hat over your sample size N. Well, if we're dealing with a 99% confidence level, the critical value is going to be 2.576. Also in our error bound formula or margin of error formula, I need Q hat. Q hat is always one minus P hat, one minus point 15. That would be point 85. Sample size is going to be 300. In the error bound formula, plug in all of these known values at 2.576 times the square root of point 15 times point 85 divided by 300. And at the end of the day here, your error bound or margin of error is going to be point to three decimal places, point 0531. So to find the confidence interval, I take my sample proportion and I will subtract my margin of error. So I'll take point 15 minus point 0531. It's going to give me point 097 to three decimal places. Then I have P hat plus E, which is point 15 plus point 0531. And this is going to give me about point 203. So my confidence interval for P is going to be between point 097 and point 203. And what this is telling me is that the true proportion of people with kids is somewhere between point 097 and point 203 or somewhere between about 9.7% and 20.3% that is the true population proportion of people that have kids. Now to use technology to get this for us because this can be a very tedious calculation, we're going to go to Google Sheets. We will go to the data list tab and we're doing a confidence interval for a proportion. So go to columns DNA, you see one proportion confidence level P value. X is the number of successes, so number of people that have kids. In this case, it turned out that 45 out of 300 had kids. So 45 is X, 300 is N. You don't need to worry about anything in the next two cells, but the confidence level should probably go ahead and put that the confidence level is going to be point 99. And once you do that, you should see that your lower confidence interval limit is going to be point 097 and then your upper limit is going to be point 203. And if you look at our information or answer here, that's exactly what we got, point 097, point 203. That's all I have for you today. Thank you.