The standard deviation of the market$-$index portfolio is $10\%.$ Stock has a beta of $2\mathrm{.}70$ 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.$)$ Answer is complete and correct. b$.$ Calculate the total variance for an increase of $20\%$percentage points in its residual standard deviation. $($Do not round intermediate calculations.$)$