The point of step three was ultimately to find the test statistic. The test statistic, which is to tell us how weird, how unusual these samples are, to then find the P-value. Which would tell me how unusual, like just literally how surprising is this sample. And now, could you use this huge formula to find this test statistic? Sure, you could, but I am not going to ask you guys to use this formula because it's a lot of work. A lot of little algebra mistakes can happen and frankly, your calculator can do the math for us. So, can I get a little bit of celebration? You do not need to do this formula. Please don't use this formula. All right, ultimately, to calculate that all-important P-value, I want you guys to use your calculator. Use your TI84 calculator when it comes to calculating any hypothesis testing, frankly, even confidence intervals. We're going to go back to our friend, the "Stat" button. Go back to that right-hand column of "Test". And now, we are going to choose 2-PropZTest. Now, we're going to choose that sixth option of 2-PropZTest and going down to our apnea question. I want to particularly write in your notes why are we specifically using 2-PropZTest? Just like we saw in chapter 7.5. In particular, the number in front of our test, whether it was one or two, signified how many populations we are looking at. And remember, the number two is emphasizing we're looking at two populations. We are looking at infants who got therapy and infants who didn't. Remember that literally this entire time in chapter seven and eight, we have the middle of the test be prop. Why? Because we are studying the proportion. What proportion of the infants suffered and like we've seen throughout chapter eight, the test is to emphasize I am running a hypotheses test. So I want you to see the name. The name of the test function lends itself to what we are even trying to do in this problem. Two population proportion hypothesis test. And that when it comes to looking at the 2-PropZTest, literally inside the test function, it's going to explicitly tell you find X1, find N1, find X2, find N2. And what I want to emphasize to you guys is that these values of X1, N1, X2, N2, they are all values that are ultimately found in the prompt. All right, I want to emphasize these are all values found in the prompt. Why? Because X1 is representing the number of successes from the sample. Remember N1, N2 are representing the sample size. Ultimately, when you're typing into 2-PropZTest, we're wanting to type in information from the sample. But here's the beautiful part is we've actually already identified X1, N1, X2, and N2. Remember when it came to doing the poed sample proportion calculation? Every number we needed to plug into that formula is X1, N1, X2, N2. So the cool thing is you already identified those numbers. We've already identified those numbers in orange in the prompt. And so I want to emphasize to you guys that in a lot of ways step three is really easy because it's just going to be about identifying those numbers and just plopping it into to our calculator. X1 was that 377, N1 was that 937 coming from group one. Remember X1 and N1 are emphasizing group one whereas X2 is 431, N2 is 932 again it's the information from group two so you just want to emphasize these numbers come to directly from our prom so let's type those in 377, 937, 431, 932. And so what then is the last thing we need to do? Well, once again, pick my inequality. But again, I want to emphasize to you guys, don't reinvent the wheel—literally. You want to see your step one because we already did this. We already identified which inequality to use all the way back in step one. Remember? All the way back in step one, we ultimately said we use the word "lower," which meant less than. And so because of that, because of that, you don't even need to reinvent the wheel to ultimately find that inequality. You just look at the fact we said "lower" and "lower" emphasizes "less than," "less than." So, I want to just emphasize that step three is really straightforward if you've properly identified all of your values. We hit calculate. If we hit calculate, we will see here my P-value is for some of you written as 4.4 E -3 or if you write it as a decimal of 0.0044. Now, can you guys remind me really quick when we had situations where your P-value ended with e negative something, it pretty much ended up with a number that was very, very small. 0.044 is very small. So, in particular, when you get this very, very, very small number, this e negative number, in essence, what value is the P-value? What number is the P-value? You guys remember? Yeah, it's pretty much zero.