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c) A study of the shares quoted on the stock exchange suggests that the average variance of returns is 270 and the average covariance is 140. i. Determine the expected risk of a portfolio made up of 60 randomly chosen and equally weighted securities. (4 marks) ii. Draw a diagram to illustrate the general form of the relationship expected between the standard deviation of the returns on portfolios and the number of randomly chosen and equally weighted securities included in these portfolios. (2 marks) Discuss the nature of the relationship you have identified and comment on its implications for the possibilities offered for reducing an investor's risk exposure (4 marks)