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Hi, i'm david and i'm here to help you answer your question.
00:03
Now let me bring up your question here.
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In this question we discuss about the comfort interval.
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Now in order to discuss about the comfort interval, there's two types of the comfort interval when we have the sigma is known and the sigma is unknown.
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When the sigma is known, we have the confidence interval is given by x bar plus and minus z and 4 over 2 times the sigma of the square root of the x.
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When the signal is unknown, we will have the x bar plus or minus.
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This will be the t now, and minus 1 degree of freedom, and then unfath over 2.
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And this will be the s will be the estimated standard deviation over square of the n.
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Now in this question here, we're given the n equal to the 20.
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We found the complete interval.
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This will be 95 % equal to 4 .5 % equal to 4 .5 .1.
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And 5 .191 and we have the 95 competitive for the mean for the normal population.
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They ask you to find the sample variance s and it means that we have to use the second one because the ask you to find the s...