00:01
For this problem, to begin, we know that our claim is that the mean value is less than three days.
00:07
Because this is a strict inequality, that's going to be our alternate hypothesis, mu less than three.
00:14
Our null hypothesis then will be that mu is greater than or equal to three.
00:21
Now the way that we'll test this, i'll note that the population standard deviation is unknown, so this is going to be done as a left tail t -test.
00:34
We know that we are testing at a level of significance of 0 .05, so our first step here is going to be to find our, or my first step that i'll take here is to find the critical value, t star.
00:51
That will be the negative t score for n minus one degrees of freedom.
00:56
We're told that we have a sample of forty orders being tracked, so that's 39 degrees of freedom there.
01:01
And we want a tail proportion of 0 .05...