4. Avicorp has a $14.6 million debt issue outstanding, with a 6.1% coupon rate. The debt has semi-annual coupons, the next coupon is due in six months, and the debt matures in five years. It is currently priced at 93% of par value. a. What is Avicorp's pre-tax cost of debt? Note: Compute the effective annual return. b. If Avicorp faces a 40% tax rate, what is its after-tax cost of debt? Note: Assume that the firm will always be able to utilize its full interest tax shield. a. The cost of debt is % per year. (Round to four decimal places.) b. If Avicorp faces a 40% tax rate, the after-tax cost of debt is %. (Round to four decimal places.)