Benco Limited is considering two mutually exclusive projects whose expected Net cash flow are given below: YEAR PROJECT(S) PROJECT (R2 '000' '000' 2000 (80,000) (60,000) 2001 20,000 10,000 2002 60,000 35,000 2003 50,000 40,000 2004 40,000 10,000 2005 30,000 20,000 If Bence Ltd intends to diversity risks and invest 50% of the resources in project (S) and 50% in project (R). a. Compute the return of the portfolio (3 marks) b. Compute the variance and standard deviation of the portfolio (7 marks)