0:00:00.320,0:00:04.861
So, let's again look at how we solved for the last confidence interval. We still
0:00:04.861,0:00:10.938
know that the true population mean, Mu sub BT, is going to be within 1.96
0:00:10.938,0:00:18.192
standard deviations of our sample mean. So, our sample mean is 40. And if we
0:00:18.192,0:00:26.528
subtract 1.96 standard deviations, we subtract 1.96 times 1.01. So this is
0:00:26.528,0:00:33.039
38.02, approximately. And then, to find the upper bound of this confidence
0:00:33.039,0:00:39.438
interval, we just add 1.96 standard deviations from the mean. So, this is about
0:00:39.438,0:00:45.570
41.98. It's pretty simple when we lay it out like this, just generically x bar
0:00:45.570,0:00:50.970
plus or minus the z score, in this case 1.96 since we want a 95% confidence
0:00:50.970,0:00:56.780
interval, times the standard deviation. But, really understanding the concept of
0:00:56.780,0:01:01.427
the confidence interval is really complicated. So, if you need to, keep
0:01:01.427,0:01:06.305
replaying these videos. Keep thinking about it. Don't worry. It took me a really
0:01:06.305,0:01:11.582
long time. I'm still completely understanding this stuff. It's complicated and
0:01:11.582,0:01:14.673
it requires some thought and patience.