Two confidence intervals. The data used for Exercise 10.49 include 195 men 30 years old. The mean income of these men is y = $49,880 and the standard deviation of these 195 incomes is sy = $38,250.

(a) Use the one-sample t procedure to give a 95% confidence interval for the mean income μy of 30-year-old men.

(b) Why is this interval different from the 95% confidence interval for μy in the regression output? (Hint: What data are used by each method?)

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