Question 490833
A confidence interval estimate for the population mean is given to be (47.81, 56.24). If the standard deviation is 16.555 and the sample size is 42, answer each of the following (show all work): 

(A) Determine the maximum error of the estimate, E.
The width of the CI is ALWAYS 2*E
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2E = (56.24-47.81)
2E = 8.43
E = 4.265
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(B) Determine the confidence level used for the given confidence interval.
E = z*s/sqrt(n)
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Solve for "z":
4.365 = z*16.555/sqrt(42)
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z = 1.7088
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Find the right-tail associated with z = 1.7088
Normalcdf(1.7088,100) = 0.0437
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Confidence level = 2*0.0437 = 8.75%
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Cheers,
Stan H.
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