A sample of 22 observations is selected from a normal populationfor which the population standard deviation is known to be 8. Thesample mean is 27.
a. Determine the standard error of the mean.(Round the final answer to 3 decimal places.)
The standard error of the mean is.
b. Explain why we can use formula (8–1) todetermine the 90% confidence interval, even though the sample sizeis less than 30.
(Click to select)Ă‚Â Ă‚Â The population is normallydistributed and the population variance is unknown.Ă‚Â Ă‚Â Thepopulation is normally distributed and the population variance isknown.Ă‚Â Ă‚Â The population is normally distributed and thesample variance is known.
c. Determine the 90% confidence interval forthe population mean. (Round the intermediate calculation to3 decimal places. Round the final answers to 3 decimalplaces.)
The 90% confidence interval for the population mean is betweenand.
