00:01
So what we're looking at today is the age of students at our university.
00:10
And we're given a lot of other information.
00:12
We're given the id number.
00:14
We're also given...
00:15
And this is the age.
00:16
So this is the age of students, of a sample of students from our university.
00:23
And we're given the id.
00:27
We're given the sex.
00:30
I said we're given the age and it's given already.
00:32
That's why i have showing.
00:34
And we're given the height.
00:36
And we're also given the college year.
00:41
I mean like third year, fourth year, fifth year, sixth year, et cetera.
00:46
How many times, how long you've been at the school.
00:49
And we only need the age.
00:52
So i removed everything else because what we're looking for is we wanted to see how our university's mean age compares to the population mean age of traditional on -ground universities.
01:04
So our null hypothesis is that the mean is equal to 21.
01:14
We're told the population mean of college students on traditional on -ground universities is 21.
01:21
And this sample is from our university.
01:24
And so we're gonna test this against our population mean of 21.
01:29
So not equal to 21.
01:30
Is our sample mean different than 21? that's what we're looking for.
01:33
And we're gonna do a one sample t -test to test these hypotheses.
01:47
And we're not given an alpha, but a lot of times you compare that you need, you do need an alpha and we're gonna set one.
01:57
We'll say alpha is 0 .05.
01:59
And so what that means is using the t -value approach, we're going to reject the null hypothesis.
02:04
Say our sample mean, our mean university or our university's mean age is different than 21.
02:12
If we're gonna reject h -naught, if the test statistic, the absolute value of our test statistic is greater than some critical value.
02:22
And the critical value is based on the alpha and the alpha 0 .05, but we're gonna cut it in half.
02:32
And then we also need our degrees of freedom.
02:34
And our degrees of freedom is given as n minus one.
02:38
So there are a total of 40 people in our sample.
02:42
So 40 minus one degrees of freedom is gonna be 39.
02:48
All right.
02:48
So the way we calculate our test statistic, t is equal to x -bar, our sample mean, minus that population assumed mean of 21 divided by s divided by the square root of the sample size.
03:01
S is the sample standard deviation...