00:01
We're taking random samples of size 81, so that's important, i'll note that down.
00:06
Sample size n equals 81, from a population whose mean, so the population mean is 200, and the standard deviation, sigma, is 18.
00:18
We want to know the expected value and the standard error of the sample mean.
00:24
Okay, so we're taking a lot of samples of size 81, and we're comparing these samples.
00:30
We take the mean of the sample means, and we take the standard deviation of the sample means.
00:39
What do we see? well, first of all, the mean of the means is just going to be 200.
00:47
There's no reason we would expect it to skew either way.
00:50
Some of them are going to have a lower sample mean, some are going to have a higher sample mean, but they will average out to be the same as the population mean...