II. On average, 15 air accidents occur each year. (The World Almanac and Book of Facts, 2004). (11 pts) a) Calculate the average number of plane crashes per month. (2 sts.) b) Calculate the probability that there will be no accidents in a month. (2 sts.) c) Calculate the probability that there is exactly more than one accident in a month. (4sts.) d) What is the variance of this distribution? (1 sts.) e) What is the standard deviation of this distribution? (2 sts.)