00:01
Today, everyone.
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So here to find the 90 % interval, so we're going to use the formula, x positive negative z.
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We have the variance divided by the squared of n.
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Where our mean is equal to 774 .94.
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Our confidence, so we have our confidence, so which is our z is 1 .642 at 90%.
00:35
So the standard division is 738 .4.
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So we have the sample size, which is our n, that is 400.
00:48
So we have 774 .94 .94, positive negative 1 .642.
00:55
So we have 738 .40 divided by square of 400.
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So we just need to simplify.
01:04
So we have 7754 .94, positive, negative, 60 .62 or this gives us the interval that is 714 .32 to 836 .56.
01:21
Now for part b, we have part b, we have the mean is equals to 187.
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So we have 187.
01:35
So we have the confidence...