Here are returns and standard deviations for four investments. Calculate the standard deviations of the following portfolios. a. 50% in Treasury bills, 50% in stock P. b. 50% each in Q and R, assuming the shares have: Complete this question by entering your answers in the tabs below. 50% each in Q and R, assuming the shares have: Note: Do not round intermediate calculations. Enter your answers as a percent rounded to 1 decimal place