Please be specific, answer all parts step by step, and show the formula you use. Thank you!

2. The securities of companies Z and Y have the following expected returns and standard deviations: Company Z 15 20 Company Y Expected Return (%) Standard Deviation (%) 35 40 Assume that the correlation between the returns of the two securities is 0.25. (a) Calculate the expected return and standard deviation for the following portfolios: 1) 100% (2) 75%Z 25% (3) 50%Z + 50%Y (4) 25%X + 75%Y (5) 100%Y (b) Graph your results (standard deviation on the X axis, Expected return on the Y axis). (c) Which of the portfolios in part (a) is not optimal? Explain