00:01
All right, so here you've got a study where you have 50 subjects, and you're given a mean from this study of 4 .7, standard deviation of 15 .8.
00:13
You're going to make a 99 % confidence interval to estimate the mean.
00:20
So that's what we're going to do.
00:21
So to do that, here's your formula for it.
00:23
They give you x bar, they give you the standard deviation, and they give you the end value.
00:28
And the x bar is up here at the mean.
00:31
So this is x bar um your standard deviations right here little sigma and then your end value is 50 that's how many subjects are in the in this uh test the z value is going to be different for what type of confidence interval you're making so that z value i mean you can have confidence intervals that are 80 85 90 99 .99 .99.
00:58
99 .9.
01:00
That z value just depends so our z value for here is going to be 2 .576.
01:07
So if i put all those things in, my x bar was 4 .7.
01:15
And the plus minus means you go through it once with a plus and then once with a negative.
01:20
Let's say you get your two numbers for this interval.
01:23
So let's go through it once with a plus...