00:01
For your setting, you asked about using excel, and i can't help you with that, but i can help you with doing the problem.
00:06
And so we have the setup that we have 10 samples, and we know that the mean is 103 milligrams, and the sample standard deviation is 2 .22.
00:16
And you have two questions that are dealing with, assuming that the population standard deviation is 2 milligrams.
00:24
And one, you want to find out, do you have evidence that it is different from 100? and so that is a z test, but a two -tail test.
00:33
And since we have 0 .05, as our significance level, we're going to put 0 .05, we're going to put 0 .025 in each tail.
00:43
And our critical values are 1 .96 and negative 1 .96.
00:47
And so we can see where we reject the null.
00:50
And our test statistic, our z value, is 103 minus 100 over the population standard deviation over the square root of n.
01:00
Value comes out to be 4 .72.
01:03
Now that is in the rejection region.
01:07
So we have evidence to reject the null and we can say that there is sufficient evidence that the mean is different from 100.
01:15
Now question two is very similar except now it's a one tail test which means our critical value changes and our critical value is now having all 5 % in that upper tail rather than 2 .5 % for a 2 .5 % for a 2 .5 % tail test and that now changes that critical value to 1 .645 and the z value will remain the same...