Stock A$\text{'}$s $($annual$)$ expected return is $10\%$ and its $($annual$)$ volatility

is $15\%.$

$($a$)$ What is the stock's expected return over a half$-$year? $($This means

the expected value of ${\displaystyle \underset{0}{\overset{\mathrm{.}5}{}}}\frac{dS}{S}.)$

$($b$)$ What is the stock return's volatility over a half$-$year? $($This means

the standard deviation of ${\displaystyle \underset{0}{\overset{\mathrm{.}5}{}}}\frac{dS}{S}.)$