A study of natural rock slope movements in the Canadian Rockies over the past 5,000 years revealed that the number of major rockslides per 100 square kilometers had an expected value of 1.57 (Canadian Geotechnical Journal, Nov. 1985).

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 3 or more major rockslides per 100 square kilometers over a 5,000-year period?