Suppose Indigo Books and Music has a beta of $0\mathrm{.}8.$ The yield on a $3-$month T$-$bill is $4\%$ and the yield on a $10-$year government bond is $6\%.$ The market risk premium is $5\mathrm{.}5\%,$ but the stock market return in the previous years was $15\%.$ What is the estimated cost of common equity using the CAPM?

$10\mathrm{.}88$ percent

$11\mathrm{.}35$ percent

$10\mathrm{.}47$ percent

$10\mathrm{.}40$ percent