Suppose we have the following Treasury bill returns and inflation rates over an eight$-$year period:

Year Treasury Bills Inflation

$16\mathrm{.}93\%8\mathrm{.}80\%$

$28\mathrm{.}0012\mathrm{.}20$

$35\mathrm{.}807\mathrm{.}01$

$45\mathrm{.}084\mathrm{.}81$

$55\mathrm{.}126\mathrm{.}77$

$67\mathrm{.}189\mathrm{.}03$

$710\mathrm{.}3813\mathrm{.}31$

$811\mathrm{.}2412\mathrm{.}40$

a$.$ Calculate the arithmetic average return for Treasury bills and the average annual inflation rate $($consumer price index$)$ for 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 Treasury bill returns and inflation 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$.$ What is the average real return for Treasury bills 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$.,32\mathrm{.}16.)$