Question

The probability is 0.45 that a traffic fatality involves an intoxicated or alcohol-impaired driver or nonoccupant. In ten 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 a. The probability that exactly three traffic fatalities involve an intoxicated or alcohol-impaired driver or nonoccupant is 0.1664 (Round to four decimal places as needed.) The probability that at least three traffic fatalities involve an intoxicated or alcohol-impaired driver or nonoccupant is 0.9004 (Round to four decimal places as needed.) The probability that at most three traffic fatalities involve an intoxicated or alcohol-impaired driver or nonoccupant is 0.2660 (Round to four decimal places as needed.) b. The probability that between two and four taffic fatalities, inclusive, involve an intoxicated or alcohol-impaired driver or nonoccupant is 0.4811 (Round to four decimal places as needed.) c. The mean of Y is 4.5 Choose the correct interpretation of the mean below OA In every ten traffic fatalities, exactly this many will involve an intoxicated or alcohol-impaired driver or nonoccupant. O B On average, of this many traffic fataities, 1 will involve an intoxicated or alcohol-impaired driver or nonocupant. c On average, of ten traffic fatalities, this many will involve an intoxicated or alcohoHmpaired driver or nonoccupant. d. The standard deviation of Y is(Round to two decimal places as needed.)

I need help on Part D, please!!

Answer 1

This is a binomial distribution.

n = 10

p = 0.45

d) Standard deviation = sqrt(n * p * (1 - p)) = sqrt(10 * 0.45 * 0.55) = 1.57 (ans)