Consider the following rates of return:

Year Large$-$Company Stocks US Treasury Bills

$13\mathrm{.}90\%5\mathrm{.}84\%$

$214\mathrm{.}472\mathrm{.}49$

$319\mathrm{.}213\mathrm{.}72$

$414\mathrm{.}477\mathrm{.}14$

$531\mathrm{.}965\mathrm{.}26$

$637\mathrm{.}456\mathrm{.}39$

a$.$

Calculate the arithmetic average returns for large$-$company stocks and T$-$bills over this period. $($Do not round intermediate calculations and enter your answers as a percent rounded to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)$

b$.$

Calculate the standard deviation of the returns for large$-$company stocks and T$-$bills over this period. $($Do not round intermediate calculations and enter your answers as a percent rounded to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)$

c$-1.$

Calculate the observed risk premium in each year for the large$-$company stocks versus the T$-$bills. What was the arithmetic average risk premium over this period? $($A negative answer should be indicated by a minus sign. Do not round intermediate calculations and enter your answer as a percent rounded to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)$

c$-2.$

Calculate the observed risk premium in each year for the large$-$company stocks versus the T$-$bills. What was the standard deviation of the risk premium over this period? $($Do not round intermediate calculations and enter your answer as a percent rounded to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)$