Here are returns and standard deviations for four investments. Treasury bills Stock P Stock Q Stock R Return (8) 5.5 8.0 15.0 23.0 Standard deviation Standard. Deviation Calculate the standard deviations of the following portfolios. a. 50% in Treasury bills, 50% in stock P. (Enter your answer as a percent rounded to 2 decimal places.) 0 14 37 22 Perfect positive correlation Perfect negative correlation No correlation % b. 50% each in Q and R, assuming the shares have: (Do not round intermediate calculations. Enter your answers as a percent rounded to 2 decimal places.) Standard Deviation % % %