SOLUTION: A simple random sample of 40 items resulted in a sample mean of 25. The population standard deviation is 5. a. What is the standard deviation of the mean? b. At 90% confidence, w

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Question 1008340: A simple random sample of 40 items resulted in a sample mean of 25. The population standard deviation is 5.
a. What is the standard deviation of the mean?
b. At 90% confidence, what is the margin of error?
c. What is 90% confidence interval estimate for the population mean?
d. At 95% confidence, what is the margin of error?
e. What is 95% confidence interval estimate for the population mean?

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
A simple random sample of 40 items resulted in a sample mean of 25. The population standard deviation is 5.
a. What is the standard deviation of the sample means?:: 5/sqrt(40)
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b. At 90% confidence, what is the margin of error?
ME = 1.645*5/sqrt(40)
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c. What is 90% confidence interval estimate for the population mean?
25- ME < u < 25+ME
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d. At 95% confidence, what is the margin of error?
ME = 1.96*5/sqrt(40)
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e. What is 95% confidence interval estimate for the population mean?
25-ME < u < 25+ME
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Cheers,
Stan H.