1 00:00:00,220 --> 00:00:05,212 If our sample size is 100, that means we now have 99 degrees of freedom instead 2 00:00:05,212 --> 00:00:10,387 of 24. And if we look at our T table, we see that the closest degrees of 3 00:00:10,387 --> 00:00:16,630 freedom to 99 is 100. So we'll just use that one. And again we want .025 in 4 00:00:16,630 --> 00:00:23,171 each tail. Notice that it also says at the bottom Confidence level C. And here 5 00:00:23,171 --> 00:00:28,820 we have 95%. This is the same as how at the top of the column, it has .025% in 6 00:00:28,820 --> 00:00:35,152 either tail. That's equivalent to a 95% confidence interval, pretty cool. And 7 00:00:35,152 --> 00:00:42,592 we see that the t critical value is 1.984 and negative 1.984. Therefore, the 8 00:00:42,592 --> 00:00:51,708 margin of error is 1.984 times s, divided by root n. And this is 39.68. Notice 9 00:00:51,708 --> 00:00:55,677 that now the margin of error got a lot smaller than it was before with a sample 10 00:00:55,677 --> 00:01:03,430 size of 25. Before the margin of error was 2.064 times 200 divided by the 11 00:01:03,430 --> 00:01:10,410 square root of 25, which was 82.56. So when we increase the sample size, we 12 00:01:10,410 --> 00:01:16,256 decrease our margin of error, and we're more precise. And remember, when we 13 00:01:16,256 --> 00:01:21,261 increase the sample size, we also have more degrees of freedom and therefore, 14 00:01:21,261 --> 00:01:28,323 our t distribution goes from wider to skinnier as it approaches normality.