The last four years of returns for a stock are as follows:

$-4\mathrm{.}0\%-28\mathrm{.}0\%$

a$.$ What is the average annual return?

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

$=$AVERAG

E$($B$6,$C$6,$

D$6,$E$6)$

c$.$ What is the standard deviation of the stock's returns? I need the anserwer in exel formate