The weighted average cost of capital is calculated as -
WACC = (Weight of common stock X Cost of common stock) + (Weight of preferred stock X Cost of preferred stock) + (Weight of debt X After tax cost of debt)
Weight of debt and equity is calculated as -
Debt =.6 and equity = 1 as debt-equity ratio is 0.6:1
Weight of debt = .6/1.6 = 37.5 %
Weight of equity = 62.5%
Cost of equity = 14.5 % and cost of debt = 4.8% (after tax)
WACC = (62.5% X 14.5%) + (37.5% X 4.8%)
WACC = 10.86 %