On January $1,2023,$ the total market value of Fin $6020$ was $$60$ million. During the year, the company plans to raise and invest $$30$ million in new projects. The firm's present market value of capital structure is considered to be optimal. The capital structure is composed of debt, common equity $($stocks$)$ and preferred stocks. The value of debt $($bonds$)$ is $$20$ million. The value of common equity is $$30$ million. The value of preferred stocks is $$10$ million. Assume that Tax rate is $21\%.$

$(1)$ New bonds will have $8\%$ coupon rate and be sold at $$1050.$ Its maturity is $4$ years. Coupon is paid annually. Face value is $$1000.$ Estimate cost of debt of Fin $602.(10$ points$)$

$(2)$ New preferred stock will be sold at $$40.$ Its preferred stock dividend is $$4.$ Estimate cost of preferred stock $(10$ points$)$

$(3)$ New common equity will be sold at $$30.$ Its dividend will be $$3($D$1).$ The dividend payment expected to grow by $5\%$ every year forever. Estimate cost of equity $(10$ points$)$

$(4)$ Basing on information $1),2)$ and $3),$ estimate after tax weighted average cost of capitals $($WACC$)$ of Fin $602.$ Then explain why WACC is important $(10$ points$)$