The average score for a water safety instructor (WSI) exam is 75 with a standard deviation of 12. Fifty scores for the WSI exam are randomly selected. a. Find the probability that the average of the fifty scores is at least 80. b. Find the probability that the average of the fifty scores is at most 70. c. Find the probability that the average of the fifty scores is between 72 and 78. d. Find the probability that the average of the fifty score will differ from the mean score by more than 10.