00:01
Okay, so we have a null and alternative hypothesis here that we're considering.
00:04
The null hypothesis that the mean is equal to 450 and the null, sorry, alternative that the mean is not equal to 450.
00:11
We have a normally distributed population with a serene deviation of 78.
00:16
So for number one, we're supposed to calculate the value of the test statistic when we have x bar of 464 and n of 45.
00:24
So this is pretty straightforward one sample z test for means.
00:30
It's a z test because i have the standard deviation of the population.
00:36
So the z test statistic is going to be calculated as x bar minus the mean from the null hypothesis divided by sigma over the square root of n.
00:47
So that will be 464 minus 450 over 78 over the square root of 45 in this case.
00:56
Right, so put that in my calculator really quickly.
01:01
Let's see it divided by 70 over the square root of 45 and i get 1 .20 for my test statistic.
01:12
Okay? so for the second question, it says what is the conclusion at the 10 % significance level? right.
01:23
So to find out what my p value is to know whether or not to reject it, i need to look at 1 .20.
01:31
On my on my z chart right and this is definitely going to give me a large p value because it's a two -tail test which means that i need like both of these tails right here right so when i look up 1 .2 and i look up the value in the tail for that it ends up being 0 .115 1 but then this area is also 0 .1151 right so the total p value is 0 .11511 times 2, which is 0 .2302, right? so that's obviously greater than our alpha of 0 .1, which is 10%.
02:17
So we are going to fail to reject the null hypothesis or do not reject the null hypothesis, right? since the p value is greater than the alpha.
02:34
So then this means that we, for the, for the, for the, third part right for number three, we cannot conclude that the sample mean differs, or sorry, that the population mean differs.
02:51
Okay...