问题如下：
A Treasury bond has a coupon rate of 6% per annum (the coupons are paid semiannually) and a semiannually compounded yield of 4% per annum. The bond matures in 18 months and the next coupon will be paid 6 months from now. Which number of years is closest to the bond’s Macaulay duration?
选项： A. 1.023
years
B. 1.457
years
C. 1.500
years
D. 2.915
years
解释：
ANSWER: B
For coupon-paying bonds, Macaulay duration is slightly less than the maturity, which is 1.5 years here. So, B would be a good guess. Otherwise, we can compute duration exactly.
老师能详细解释一下这道题吗
