7. You recently purchased a stock that is expected to earn 20 percent in a booming economy, 10 percent in a normal economy, and lose 30 percent in a recessionary economy. There is a 5 percent probability of a boom and a 75 percent chance of a normal economy. What is the expected rate of return and standard deviation on this stock?

8. Your portfolio is comprised of 40 percent of stock X, 15 percent of stock Y, and the rest in stock Z. Stock X has an expected return of 10%, stock Y has an expected return of 15%, and stock Z has an expected return of 2%. What is the expected return of your portfolio?

9. Your portfolio is comprised of 20% of stock X, 40% of stock Y, and the rest in stock Z. Stock X has an expected return of 12% and stock Y has an expected return of 20%. If the portfolio has an expected return of 15%, what is the expected return of stock Z?