A researcher would like to estimate the average age of a student at a large university to within 1.5 years. How large a sample would she need to obtain in order to be 95% confident if the standard deviation is known to be 5.8 years?
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For a 95% confidence level, the z-score that corresponds to the middle 95% of a standard normal distribution is approximately 1.96. This value can be found in z-tables or standard normal distribution tables. Show more…
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