问题如下图：
选项：
A. 
B. 
C. 
解释：
请问这道题在计算的时候为什么使用0.5乘以后面完全一样的两倍的数字，完全可以不乘啊，原理是什么呢？（求老师不要告诉我都一样，我就是比较好奇这么算的原理，害怕是自己漏掉了哪个知识点）
NO.PZ201712110200000203 问题如下 Baseon Exhibits 3 an4, the value of BonC the upper no Time 1 is closest to: A.97.1957 B.99.6255 C.102.1255 B is correct. The bonvalue the upper no Time 1 is closest to 99.6255. The cash flow Time 2 is 102.5, the remption of pvalue (100) plus the fincoupon payment (2.5). Using backwarinction, we calculate the present value of the bonthe upper no of Time 1 102.5/1.028853 = 99.6255. 为啥value不用加coupon, 也可以是time 1付息前的价值啊
NO.PZ201712110200000203问题如下Baseon Exhibits 3 an4, the value of BonC the upper no Time 1 is closest to:A.97.1957B.99.6255C.102.1255B is correct. The bonvalue the upper no Time 1 is closest to 99.6255. The cash flow Time 2 is 102.5, the remption of pvalue (100) plus the fincoupon payment (2.5). Using backwarinction, we calculate the present value of the bonthe upper no of Time 1 102.5/1.028853 = 99.6255.我算出来的是99.9292，跟答案小数差了一点
NO.PZ201712110200000203 问题如下 Baseon Exhibits 3 an4, the value of BonC the upper no Time 1 is closest to: A.97.1957 B.99.6255 C.102.1255 B is correct. The bonvalue the upper no Time 1 is closest to 99.6255. The cash flow Time 2 is 102.5, the remption of pvalue (100) plus the fincoupon payment (2.5). Using backwarinction, we calculate the present value of the bonthe upper no of Time 1 102.5/1.028853 = 99.6255. 请问这个两年的二叉树，拿到coupon+par的这一年是第二年吗？ 我一直以为两年的二叉树是time 0, time 1, time2， 然后time 2之后拿到coupon+par，再用time 2 的利率开始折。
99.6255 102.1255 B is correct. The bonvalue the upper no Time 1 is closest to 99.6255. The cash flow Time 2 is 102.5, the remption of pvalue (100) plus the fincoupon payment (2.5). Using backwarinction, we calculate the present value of the bonthe upper no of Time 1 102.5/1.028853 = 99.6255.看了大家提问的解析，还是没看懂这里为什么不加上2.5的coupon，如果不单列，也不用加上是吧。
99.6255 102.1255 B is correct. The bonvalue the upper no Time 1 is closest to 99.6255. The cash flow Time 2 is 102.5, the remption of pvalue (100) plus the fincoupon payment (2.5). Using backwarinction, we calculate the present value of the bonthe upper no of Time 1 102.5/1.028853 = 99.6255.关于这一条是否加当期的coupon，我没有看懂老师们的解答，我没有在二叉树中看到单列的coupon，所以我这题会选择包含coupon的102.1255，感觉没有明白什么是单列的coupon？
