Use the information below for Problems 18 22. Day % Return (X) % Return (Y) -9 12 3 -8 4 3 -7 -6 3 -6 2 3 -5 -3 3 -4 -1 3 -3 3 3 -2 -2 3 -1 8 3 0 3 3 18. Find the sample standard deviation of each asset. Which asset is safer based on standard deviation? 19. What is the geometric mean of returns for Asset X? 20. What is the correlation coefficient of the returns of X and Y? 21. Now assume that X and Y make up a portfolio. What is the portfolio standard deviation of returns? Treat the data as a sample. 22. Based on your answer for Problem 21, what percentage of risk is reduced by forming a portfolio of X and Y instead of holding X in isolation?