Here are returns and standard deviations for four investments.

	Return (%)	Standard Deviation (%)
Treasury bills	6.0	0
Stock P	10.5	13
Stock Q	16.5	31
Stock R	20.5	23

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 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
Perfect positive correlation	%
Perfect negative correlation	%
No correlation	%