As reported in the chapter opener “USA and Its Automobiles,” Americans are in love with the automobile—the majority have more than one vehicle per household. In fact, the national average is 2.28 vehicles per household. The number of vehicles per household in the United States can be described as follows: Vehicles, x P(x)
1............ 0.34
2............ 0.31
3............ 0.22
4............ 0.06
5............ 0.03
6............ 0.02
7............ 0.01
8............ or more 0.01
a. Replacing the category “8 or more” with exactly “8,” find the mean and standard deviation of the number of vehicles per household in the United States.
b. How does the mean calculated in part a correspond to the national average of 2.28?
c. Explain the effect that replacing the category “8 or more” with “8” has on the mean and standard deviation.