Here are returns and standard deviations for four investments. Return Standard Deviation Treasury bills 5.5% 0% Stock P 8.0 14 Stock Q 15.0 37 Stock R 23.0 22 Calculate the standard deviations of the following portfolios. a. 50% in Treasury bills, 50% in stock P. (Do not round intermediate calculations. Round your answer to 2 decimal places.) Standard deviation % b. 50% each in Q and R, assuming the shares have: (Do not round intermediate calculations. Round your answers to 1 decimal place.) Standard Deviation Perfect positive correlation % Perfect negative correlation % No correlation %