(5) In a random sample of 21 ?people, the mean commute time towork was 31.5 minutes and the standard deviation was 7.3 minutes.Assume the population is normally distributed and use a?t-distribution to construct a 80?% confidence interval for thepopulation mean ?. What is the margin of error of ??? Interpret theresults.
(8) Use the standard normal distribution or the? t-distributionto construct a 99?% confidence interval for the population mean.Justify your decision. If neither distribution can be? used,explain why. Interpret the results. In a random sample of 17mortgage? institutions, the mean interest rate was 3.69?% and thestandard deviation was 0.38?%. Assume the interest rates arenormally distributed.
(3)
Construct the indicated confidence interval for the populationmean ? using the? t-distribution. Assume the population is normallydistributed. c= 0.99?, overbar x=12.9?, s= 4.0?,n=5 round to onedecimal place
