4. You are looking to invest to IBM and Apple stocks. Their historical returns for the past 4 years are found in the following table. (8 marks) 2017 2016 2015 2014 IBM 20% -14% -14% APPLE 10% -5% 38% 6% a. What is the sample standard deviation for each stock? (4 marks) b. You decided to construct a portfolio that invests 40% to IBM and 60% to Apple. Calculate the portfolio return in 2017. (2 marks) c. The correlation coefficient of returns is -0.18. Use the standard deviation of the stocks calculated from a. to calculate the standard deviation of your portfolio using the following formula: (2 marks) Sp = V ws? + ws? + 2 w/WPiS;S