4. You are given the following information about a book of business comprised of 100 insureds: 1 (i) Xi = Ni Yij is a random variable representing the annual loss of the ith insured. j=1 (ii) N1, N2, . . . , N100 are independent random variables distributed according to a Negative Binomial distribution with parameters r (unknown) and = 0.2. (iii) The unknown parameter r has an Exponential distribution with mean 2. (iv) Yij are independent random variables distributed according to a Pareto distribution with = 3.0 and = 1000. Determine the Bu hlmann credibility factor, Z, for the book of business.