SOLUTION: The register at school wishes to determine how many student records to review in order to estimate the arithmetic mean grade point average of all graduating seniors over the last 1

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Question 889379: The register at school wishes to determine how many student records to review in order to estimate the arithmetic mean grade point average of all graduating seniors over the last 10 years. These GPA's range from 2.0 to 4.0 we wish to estimate the mean GPA to a plus or minus 0.05 of the population mean. The standard deviation is estimated to be 0.279. For a 90% confidence interval, how many records should be reviewed?
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
The register at school wishes to determine how many student records to review in order to estimate the arithmetic mean grade point average of all graduating seniors over the last 10 years. These GPA's range from 2.0 to 4.0 we wish to estimate the mean GPA to a plus or minus 0.05 of the population mean. The standard deviation is estimated to be 0.279. For a 90% confidence interval, how many records should be reviewed?
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n = [z*s/E]^2
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n = [1.645*0.279/0.05]^2 = 85 when rounded up
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Cheers,
Stan H.
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