
So, let's again look at how we solved for the last confidence interval. We still

know that the true population mean, Mu sub BT, is going to be within 1.96

standard deviations of our sample mean. So, our sample mean is 40. And if we

subtract 1.96 standard deviations, we subtract 1.96 times 1.01. So this is

38.02, approximately. And then, to find the upper bound of this confidence

interval, we just add 1.96 standard deviations from the mean. So, this is about

41.98. It's pretty simple when we lay it out like this, just generically x bar

plus or minus the z score, in this case 1.96 since we want a 95% confidence

interval, times the standard deviation. But, really understanding the concept of

the confidence interval is really complicated. So, if you need to, keep

replaying these videos. Keep thinking about it. Don't worry. It took me a really

long time. I'm still completely understanding this stuff. It's complicated and

it requires some thought and patience.