For Exercises 4.90 and 4.91, see page 212; for 4.92, see page 214; and for 4.93, see page 216.
4.91 How many cars?
Choose an American household at random and let the random variable X be the number of cars (including SUVs and light trucks) they own. Here is the probability model if we ignore the few households that own more than five cars:
Number of cars X | 0 | 1 | 2 | 3 | 4 | 5 |
Probability | 0.09 | 0.36 | 0.35 | 0.13 | 0.05 | 0.02 |
4.91
(a) 0.09+0.36+0.35+0.13+0.05+0.02=1. It is a legitimate discrete distribution. (b) The American household owns at least one car. P(X≥1)=0.91. (c) 20%.