IW 5-B Part 1 of 7 The probability is 0.45 that a traffic fatality involves an intoxicated or alcohol-impaired driver or nonoccupant. In seven 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 (Round to four decimal places as needed.)