You find a certain stock that had returns of $13$ percent, $-21\mathrm{.}5$ percent, $27\mathrm{.}5$ percent, and $18\mathrm{.}5$ percent for four of the last five years. Assume the average return of the stock over this period was $11$ percent.

a$.$ What was the stock's return for the missing year?

Note: Do not round intermediate calculations and enter your answer as a percent rounded to $2$ decimal places, e$.$g$.,32\mathrm{.}16.$

b$.$ What is the standard deviation of the stock's returns?

Note: Do not round intermediate calculations and enter your answer as a percent rounded to $2$ decimal places, e$.$g$.,32\mathrm{.}16.$

$\backslash$table$[[$a$.$ Missing return,$\%$