7. Heath食品公司債券還有7年到期，它的面額為1,000元，到期收益率是 8% ，每年付息一次，票面利率為 9% ，則它的當期收益率是多少？(8分)

8. A bond's rating provides a guide to its price. As we write this in 2009, Aaa bonds yield $5.45\%$ and Baa bonds yield $8.67\%$. If some bad news causes a $10\%$ five year bond to be unexpectedly downrated from Aaa to Baa, what would be the effect on the bond price? (Assure annual coupons with face value $1,000) (10分)