In a given year in the United States, the probability of death in a motor vehicle accident equals 0.0001 for females and 0.0002 for males (Statistical Abstract of the United States).

(a) In a city having 1 million females, find the mean and standard deviation of x = number of deaths from motor vehicle accidents. State the assumptions for these to be valid.

(b) Would it be surprising if x = 0? Explain. (Hint: How many standard deviations is 0 from the expected value?)

(c) Based on the normal approximation to the binomial, find an interval within which x has probability 0.95 of occurring.

Concepts and Applications