利息理论里3.4的一道题。虽看了solution manual，但还是不明白，现小弟把题和solution都给各位前辈写出来，求各位解释一下这个solution，或者给个新解吧。
Payment of $100 per quarter are made from June 7, Z through December 7, Z+11, inclusive. If the nominal rate of interest convertible quarterly is 6%:
a) Find the present value on September 7, Z-1.
b) Find the current value on March 7, Z+8.
c) Find the accumulated value on June 7, Z+12.
(我主要就不明白那么多Z到底啥意思。。)
答案是这么写的:
We will call September 7, Z-1  t=0
so that                March 7, Z+8 is t=34
and                       June 7, Z+12 is t=51
where time t is measured in quarters. Payments are made at t=3 through t=49, inclusive. The quarterly rate of interest is j=.06/4=.015.
a) PV = 100(a49-a2)=100(34.5247-1.9559)=$3256.88
b) CV= 100(s32+a15)=100(40.6883+13.3432)=$5403.15
c) AV = 100(s49-s2)=100(71.6087-2.0150)=$6959.37
看完答案我就完全不知所云了。。求教各位了。。拿手机上的论坛。。不知道该怎么悬赏。。有机会给各位发免费资料以表谢意吧