# Alternative Method Figure 7-6 and Table 7-1 summarize the decisions made when choosing between the…

Alternative Method Figure 7-6 and Table 7-1 summarize the decisions made when choosing between the normal and t distributions. An alternative method included in some textbooks (but almost never used by professional statisticians and almost never included in professional journals) is based on this criterion: Substitute the sample standard deviation s for σ whenever n > 30, then proceed as if σ is known. Using this alternative method, repeat Exercise 30. Compare the results to those found in Exercise 30, and comment on the implications of the change in the width of the confidence interval.Table 7-1 Choosing Between z and tMethodConditionsUse normal (z) distribution.known and normally distributed populationors known and n > 30Use t distribution.snot known and normally distributed populationors not known and n > 30sUse a nonparametric methodor bootstrapping.Population is not normally distributed and n ≤ 30. Exercise 30Ages of Presidents Listed below are the ages of the Presidents of the United States at the times of their inaugurations. Construct a 99% confidence interval estimate of the mean age of presidents at the times of their inaugurations. What is the population? Does the confidence interval provide a good estimate of the population mean? Why or why not? 42434646474849495051515151515252545454545455555555565656575757575860616161626464656869