00:01
All right, so we are testing the null hypothesis that the mean is equal to 14 versus the alternative that the mean is greater than 14.
00:16
And we have a sample size of 64, sample mean of 14 and a half, standard deviation of the sample is 2 .1.
00:24
We're going to make a 95 % confidence interval for mu.
00:34
And the formula for that is as follows, x bar plus minus t, alpha over two, no other degrees of freedom, times s over root n.
00:46
And again, we're making a 95 % confidence interval for mu.
00:52
So that means this alpha is 0 .05.
00:59
And we need the degrees of freedom, which is found by taking the sample size minus one.
01:04
So ours is going to be 64.
01:07
And we need that critical value.
01:14
And we should note the standard error term, somewhere we're asked to evaluate is this s over root n.
01:20
This is our standard error here, s, e.
01:24
And so 2 .1 divided by root 64, you get 0 .2625.
01:30
And our t critical value is this.
01:33
I found it by using this tinv function.
01:36
You put in this alpha, which you're going to cut in half...