Question 490833: I am really struggling with this problem...please help...thank you
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.
(B) Determine the confidence level used for the given confidence interval.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! 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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