Multiple problems are described, including mixture distributions, Bayesian statistics, random sums, bivariate normal pdf and linear regression, copula and geometric probabilities, optimal portfolio allocation and correlated stocks, Markowitz and probability bullet, and order statistics. Chapter 4: I Four important distributions in statistics i , deals with the widely used multivariate normal, chi-squared, Student I t i -, and Fisher I F i - distributions. The book belongs to I Wiley Series in Probability and Statistics i , and presents a comprehensive account on theoretical and computational statistics with practical applications and examples implemented in the R statistical software and its packages. [Extracted from the article]