00:01
The following is a solution for number two, and we're asked to find a 90 % confidence interval for the difference of two population means given this data.
00:07
Now, since the two sample sizes are less than 30, or at least one of them is less than 30, we have to use the two sample t interval instead of the z interval.
00:14
So i'm going to use a graphic and calculator here.
00:16
If we go to stat and then test, and we arrow all the way down to the zero option where it says 2samp t -int, that stands for 2 -sample -t interval, and then we click enter, and then just make sure stats is highlighted, and we punch in our data.
00:30
Here so x1 bar s1 in the next two bar s2 and an n2 so that's all the data that was there and the confidence level is 0 .9 for 90 percent then you get to this pooled and just make sure it's yes because it says that assume that the two standard deviations are the same so whenever that's the case then you can go ahead and pull them and then we calculate and we get this 11 .371 to 16 .629 so let's go and write that down so 11 .371 to 16.
01:01
629.
01:04
So that's the 90 % confidence interval.
01:06
And then similarly we're going to do a 99 % confidence interval, still using the t interval since they're both, or at least one of them is less than 30 with the sample size.
01:15
And so if we go to stat and then tests and then just go to the zero option, and we need to change this data here...