00:02
To construct a 95 % confidence interval to estimate the difference between the average miles per gallon between the two models, we're going to be using this big formula where the x bars are the sample means.
00:15
So for model a, it's 28 and model b it's 26.
00:19
So i'm going to plug in 28 and 26.
00:23
And then we're told the sample variances.
00:27
So those are going to be the s1, the s -a -squared and the s -b -squared.
00:31
That's going to be 16 and 9.
00:35
And we're also told our two group sample sizes are 55 and 65.
00:42
And the only thing we're going to have to look up is the critical value t.
00:47
We'll find that in the t distribution critical value table.
00:50
We're going to take our smaller sample size, 55, and subtract 1, which would be 54.
00:56
But there is no 54 degrees of freedom in this table.
01:00
So i'm going to use 50...