1. a) Define the concept of portfolio. The estimates or the Standard Deviation (SD), Expected Return (ER) and Covariance (COV) for four stocks are given below: Security l SD (%) ER (%) COV between A 8.50 11.50 A&B SO B 8.35 12.30 A.0 .75 66 C I 6.75 13.60 A&D D j 6.65 10.02 B&C 65 B&D 50 C& D Two investors named Mr. Ahad and Mr. Badshah are interested in sham market. Mr. Ahad invested Tk.1,70,000 in stock A, Tk.1,25,000 in slack .0 and Tk.1,05,000 in stock C and Mr. Badshah invested Tk.1,50,000 in stock B Tk.1,20,000 in stock C and Tk.1,30,000 in stock D. i. Whose portfolio gives the highest expected retum? ii. Who is a risky investor?