00:01
Okay, so i see that you need help with this question.
00:02
And so it wants you to find the 90 % confidence interval for the difference between the means between the two groups of students.
00:10
And so the first thing that you have to do is you have to pool their variance.
00:15
So i'm just going to move this over.
00:18
So first step, you have to pool their variance and pool variance.
00:25
So you're going to do your, if your sample size is 13, then your degree of freedom is going to be 12.
00:31
And then 15 for if your sample size is 16.
00:37
So you're going to do 12 times 9 squared plus 15 times 12 squared, and then you're going to divide that by 12 plus 15.
00:49
And then that's going to equal 116.
00:53
Then you're going to take the square root of 116, and that is 10 .7703.
00:58
And you're going to multiply that by 113 plus, multiply that by the square root of 113 plus 115.
01:07
I'm sorry, 116.
01:08
And then that's going to equal 4 .0216...