Here are returns and standard deviations for four investments. Standard Return (%) Deviation(%) Treasury bills Slock P Stock Q Stock R 4.0 9.5 13.5 21.5 12 25 24 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 b 50% each in and R, assuming the shares have: (Do not round intermediate calculations. Enter your answers as a percent rounded to 2 decimal places) Standard Deviation Perfect positive correlation Perfect negative correlation No correlation