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