Refer to Exercise A19.9. The economist also wanted to know whether there are differences in miles driven between cars, buses, and vans, pickups, and SUVs.

In exercise A19.9

The high price of gasoline is likely to lead to less travel. An economist specializing in energy uses wanted to learn more about driving habits, and, in particular, distances traveled by cars, buses, vans, and trucks. In the latest year data were available (2003), there were 136 million cars, 776,000 buses, and 87 million vans, pickups, and SUVs. An economist undertook a survey of each type of vehicle, recording the number of miles driven (in 1,000s). For each type of vehicle, estimate with 95% confidence the mean number of miles driven and the total number of miles driven.v