00:01
So in letter a here, we can say that since n is at least 30, we can still perform the test.
00:11
So we can perform the test statistic.
00:17
If the sample size was smaller than this, we would suppose that the population will be normally distributed.
00:24
So since we have a sample size which is quite high, in our case 40, we can still perform the task.
00:32
But using the t student distribution.
00:35
Now in letter b, we need to compute the test statistic.
00:38
The test statistic here, like i said, is given by the t student here.
00:43
And in this case, we need to put this x bar minus the value that we are testing in our hypothesis, which is 45, divided by the sample standard deviation, which is 8 .5, divided by the square root of the sample size.
01:00
So this here, if you can, compute you're going to get this test statistic.
01:06
Now in letter c we need to just draw a t student with the area that represents the p value.
01:14
So the t student is symmetric.
01:17
So this t student here has degrees of freedom.
01:21
In our case the degrees of freedom is the sample size minus 1 so in our case 39.
01:27
And the p value here since the test is to tail, why to tail? because the alternative has, in this case, the different sign.
01:39
So it is like a non -directional test.
01:42
So because of this, this means that we have two areas that represents the p value.
01:48
So the p value will be the sum of these two areas.
01:51
And how can we find this? we need to put this number here.
01:55
The positive will be here and the negative will be here...