FASS Plc is a Tanzanian Company listed on a Dar es salaam Stock Exchange $($DSE$).$ It pays a corporate income tax at $30$ percent and has the following capital structure.

$($i$)$ One million ordinary shares with a market value of $490$ shillings per share. A dividend of $70$ shillings per share has just been paid, and dividends are expected to grow by $8$ percent per year for the foreseeable future;

$($ii$)250,000$ preference shares, market value of which is $320$ shillings per share and the annual dividend of $7\mathrm{.}5$ percent has just been paid; and

$($iii$)$ One million shillings of irredeemable debenture, market value of which is $92$ percent of per. These debentures have a coupon rate of $10$ percent and the annual interest payment has just been made.

$($a$)$ What would be its overall cost of capital?

$($b$)$ Should FASS use this overall cost of capital as the discount rate when assess the acceptability of new projects? Explain.