For Exercises 10.39 and 10.40, see page 514.

Many of the following exercises require use of software that will calculate the intervals required for predicting mean response and individual response.

Question 10.39

10.39 Predicting the average log income.

In Example 10.7 (pages 511–512) software predicts the mean log income of entrepreneurs with 16 years of education to be . We also see that the standard error of this estimated mean is . These results come from data on 100 entrepreneurs.

  1. Use these facts to verify by hand Minitab’s 95% confidence interval for the mean log income when .
  2. Use the same information to give a 90% confidence interval for the mean log income.

10.39

(a) Using gives (9.72207, 10.38993). (b) For 90% confidence the interval is (9.77678, 10.33522).