Use the data described in Exercise 34 of Chapter 3 for this exercise.
a. The variable business describes the primary business in which the vehicle was used in 2002. Estimate the total miles driven for each type of business in 2002, along with a 95% CI. How is this special case of estimating a domain total?
b. Estimate the average miles per gallon (MPG) for each of the transmission types (transmssn), along with a 95% CI.
c. Estimate the ratio of miles driven in 2002 (miles_annl) to lifetime miles driven (miles_life), along with a 95% CI.