<PRE><B>Question 715968</B>
For sample mean x = 150, sample size n = 36 and sample standard deviation s = 40 find 80% confidence interval for population mean. Population standard deviation is not known, you should use formula on page 328 with t-value 
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x-bar = 150
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E = t*s/sqrt(n) = 1.3062*40/sqrt(36) = 8.708
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80% CI: 150-8.708 &lt; u &lt; 150+8.708
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Cheers,
Stan H.
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