The standard deviation of the market$-$index portfolio is $10\%.$ Stock A has a beta of $2\mathrm{.}00$ and a residual standard deviation of $20\%.$

Required:

a$.$ Calculate the total variance for an increase of $0\mathrm{.}10$ in its beta. $($Do not round intermediate calculations.$)$

b$.$ Calculate the total variance for an increase of $3$ percentage points in its residual standard deviation. $($Do not round intermediate calculations.$)$