Here are returns and standard deviations for four investments.

Return $(\%)$ Standard Deviation $(\%)$

Treasury bills $4\mathrm{.}00$

Stock P $12\mathrm{.}011$

Stock Q $13\mathrm{.}028$

Stock R $22\mathrm{.}022$

Calculate the standard deviations of the following portfolios.

a$.50\%$ in Treasury bills, $50\%$ in stock P$.($Enter your answer as a percent rounded to $2$ decimal places.$)$

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.$)$