00:01
They're telling us that the mean age at which men are married in the u .s.
00:03
Is 24 .8 years.
00:05
I'm surprised it's actually that low.
00:07
But anyway, we don't know the shape and we don't know the standard deviation.
00:13
But we have a sample of size 60 that is drawn, and we want to find what is the likelihood, and we're getting the mean of those 60, and we want to know what the likelihood is that the mean is less than 25 .1 years.
00:31
And we are to assume that the sample standard deviation is 2 .5 years.
00:37
And so our sampling distribution of x -bars will be approximately normal because of the central limit theorem.
00:46
And that sample size is sufficiently large.
00:49
And so we know that our distribution will have a mean of that same as the individual population.
00:56
And our standard error will be that 2 .5 divided by the square root of six.
01:02
60.
01:04
So let's find what this z value corresponds with the 25 .1 minus the 24 .8 divided by the 2 .5 divided by the square root of 60.
01:16
And again, we could draw a real fast little picture here, put the 24 .8 here, and we have a 25 .1 that's up here someplace, and we're trying to find this likelihood...