00:01
So for our test, that antisocial behavior inventory test, we have a mean of 55, a standard deviation of 12, and we're told that it's a normal distribution.
00:10
And we want to find if this group of people has a significantly different level.
00:16
So we will be assuming that that mean is equal to 55 for that group, and alternately it is different.
00:25
So a not equal to test.
00:27
Now, our test statistic will be a z value due to the fact that we have the population standard deviation given to us.
00:38
So we want to find what the critical value is, and this is a not equal to situation.
00:44
So the critical value that we'll use for this particular test is to split the tails and have 0 .005 in each of the upper and lower tail.
00:52
So the critical value here is a 2 .576, and this critical value is negative 2 .576.
01:00
And so we would reject if we're below that one or above that one.
01:05
Now let's calculate the standard error and then find the z score for that value.
01:11
So the standard air is going to be the standard deviation of the x bars, and we take our standard deviation for the population and divide it by the, square root of the sample size and we have a sample size of 21...