Here are returns and standard deviations for four investments. Treasury bills Stock P Stock Q Stock R Standard Return (%) Deviation (%) 4.0 0 11.0 10 15.5 38 24.0 25 Calculate the standard deviations of the following portfolios. a. 50% in Treasury bills, 50% in stock P. (Do not round intermediate calculations. Enter your answer as a percent rounded to 2 decimal places.) Standard deviation 5 % 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 31.5 % Perfect positive correlation Perfect negative correlation % No correlation %