WACC$$Market value weights The market values and after$-$tax costs of various sources of capital used by Ridge Tool are shown in the following table: B a$.$ Calculate the firm's weighted average cost of capital. b$.$ Explain how the firm can use this cost in the investment decision$-$making process. a$.$ The firm's weighted average cost of capital, rg$,$ using market value weights is $\%.($Round to two decimal places.$)($Click on the icon here e in order to copy the contents of the data table below into a spreadsheet.$)$ Source of capital Market value Individual cost Long$-$term debt $$850,0006\mathrm{.}6\%$ Preferred stock $$40,00010\mathrm{.}5\%$ Common stock equity $$400,00016\mathrm{.}8\%$