$6.$ Harrison Solar Inc. $($HSI$)$ has an estimated beta of $1\mathrm{.}27.$ Currently, the short$-$term U$.$S$.$ treasury interest rate is $4\mathrm{.}9\%$ per year. Historically in the U$.$S$.,$ returns to the broad stock market have averaged $12\mathrm{.}0\%$ per year while short term treasury interest rates have averaged $3\mathrm{.}4\%$ per year. Globally, returns to the broad stock market have averaged $9\mathrm{.}9\%$ while returns on low$-$risk investments similar to U$.$S$.$ treasuries have averaged $3\mathrm{.}9\%.$ Based on a survey of investment management professionals, the expected return to the broad U$.$S$.$ market over the next several years is $9\mathrm{.}3\%$ per year.

$($a$)$ What estimate of the market risk premium is supported by the historical U$.$S$.$ evidence?

$($b$)$ What estimate of the market risk premium is supported by the historical global evidence?

$($c$)$ Relying on the CAPM, and the historical global evidence, what is the expected rate of return on HSI common stock?