Exercise 3.16 Show that the beta factor By of a portfolio consisting of n securities with weights W1, ..., Wn is given by By = W1B1+...+Wnr, where B1, ..., Bm are the beta factors of the securities. Exercise 3.16 Show that the beta factor By of a portfolio consisting of n securities with weights W1, ..., Wn is given by By = W1B1+...+Wnr, where B1, ..., Bm are the beta factors of the securities