Suppose we have the following returns for large$-$company stocks and Treasury bills over a six$-$year period:

Year Large$-$Company stocks US Treasury bills

$13\mathrm{.}92\%5\mathrm{.}90\%$

$214\mathrm{.}182\mathrm{.}53$

$319\mathrm{.}373\mathrm{.}76$

$414\mathrm{.}317\mathrm{.}16$

$531\mathrm{.}805\mathrm{.}42$

$637\mathrm{.}086\mathrm{.}24$

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 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$.,32\mathrm{.}16.)$