Question

The probability is 0.45 that a traffic fatality involves an intoxicated or​ alcohol-impaired driver or nonoccupant. In nine traffic​ fatalities, find the probability that the​ number, Y, which involve an intoxicated or​ alcohol-impaired driver or nonoccupant is

a. exactly​ three; at least​ three; at most three.

b. between two and four​, inclusive.

c. Find and interpret the mean of the random variable Y.

d. Obtain the standard deviation of Y.

Answer 1

Let Y denote the number of fatalities that involve an intoxicated or​ alcohol-impaired driver or non-occupant. Then

a)

b)

c)

Mean = np = 9(0.45) = 4.05

This means that the expected number of fatalities involving an intoxicated or​ alcohol-impaired driver or non-occupant out of 9 fatalities is 4.05.

d)

Standard Devation =