Here are returns and standard deviations for four investments. Standard Deviation Treasury bills Stock P Stock Stock R Return (%) 6.0 9.5 16.0 21.5 0 14 25 27 Calculate the standard deviations of the following portfolios. a. 50% in Treasury bills, 50% in stock P. (Enter your answer as a percent rounded t Standard deviation % b. 50% each in Q and R, assuming the shares have: (Do not round intermediate calc rounded to 2 decimal places.) Standard Deviation % % Perfect positive correlation Perfect negative correlation No correlation % % %