00:01
We have been given some sample data.
00:03
The sample size n is 25, the sample mean x -bar is 72, sample standard deviation s is 22.
00:13
We want a confidence interval for the population mean mu.
00:17
The formula we need is x -bar, the point estimate, plus and minus the margin of error, ts over root n.
00:26
S over root n is our estimate of the standard error, sigma over root n.
00:30
T is the critical value.
00:33
It's not the only critical value, there's also z, and z is preferable but we do not meet the requirement to use it.
00:38
The sigma, population standard deviation, should be known.
00:42
Here it is unknown so we have to use t...