00:01
So consider the following hypothesis test.
00:03
So we have the 80 is equal to mu equals to 80.
00:07
And the alternative is the different sign.
00:12
So mu is different than 80.
00:14
We have a sample size of 50.
00:16
And we want a level significance equals to 0 .01.
00:22
So in letter a, we want to find what is the test or the t value, but it's the test statistic for when we are assuming that the simple means equals to 83 and the same percent deviation is equals to 10.
00:40
So in this case, we can use a t value here because it is related to the t student distribution.
00:49
But in this case, the formula is given by x more minus the value that we are testing our hypothesis divided by s divided by the square root of x.
00:59
So the value that we are testing here is this number here in the new hypothesis.
01:06
So we are testing if the population mean is equal to 80.
01:10
So this number here should be equals to the number that we are testing in our hypothesis.
01:17
So if you just plug the other information that we also have from the question, we are going to find that the t value is equal to 2 .12.
01:27
Now the p value, since this test is a two -tail or two -sided test, this is given by the probability of the module of a t -student distribution being greater than the level or the t -value that we found, which is 2 .12.
01:48
So if you open the module here, you're going to find that this is the sum of two areas in the t -student, which is given.
01:58
By the t student less than the negative of the t value plus the area in which the t student is greater than the positive value of the t value.
02:11
And now we can assume that the t, not assume, but it's a fact.
02:16
The t student is symmetric.
02:18
So these two probabilities are equal.
02:22
So we can just compute two times one of them and say that this is the t, the t's symmetric.
02:28
Value that we want.
02:29
So let's choose the first one.
02:31
And to compute this probability, we need to specify what is the degrees of freedom of this t student.
02:38
So the degrees of freedom of this t student is the sample size minus one.
02:44
So we're assuming that this t student has 49 degrees of freedom.
02:49
And assuming this, you are going to find using a t -table that this probability is equal to 0 .0195, which is 0 .039.
03:01
So in this case, we can say that this number belongs, in this case, between 0 .025 and 0 .05...