4. [15 points] A study of natural rock slope movements in the Canadian Rockies over the past 5,000 years revealed that the number of major rock slides per 100 square kilometers had an expected value of 1.57 major rockslides. a. Find the mean and standard deviation of Y, the number of major rockslides per 100 square kilometers in the Canadian Rockies over a 5,000 year period. b. What is the probability of observing 4 or more major rockslides per 100 square kilometers over a 5,000 year period? c. Compute the P 06-20 S Y 5 p+20)