I've got a rainbow annuity like so:

pmt: 1 2 3 .... n n n-1 .... 2 1

time: 1 2 3 .... n n+1 n+2 ...2n-1 2n

I need to compute the present value at time t = 1. My book does it by breaking it up into a bunch of value-1 annuities and then adding them up (ie, time 1 to 2n, 2 to 2n-1, etc).

*i* want to do it by treating it as two annuities, finding the present value of them, and combining them.

IE: first annuity is just an increasing annuity from time 1 to n, second annuity is just a decreasing annuity from time n+1 to 2n.

HOWEVER I cannot get this to turn into the answer from the book - i'm not sure how to type these symbols into the computer either .. but take my word, I think my problem is how to 'discount' the second annuity properly to find it's present value at time 1.

Thoughts?

pmt: 1 2 3 .... n n n-1 .... 2 1

time: 1 2 3 .... n n+1 n+2 ...2n-1 2n

I need to compute the present value at time t = 1. My book does it by breaking it up into a bunch of value-1 annuities and then adding them up (ie, time 1 to 2n, 2 to 2n-1, etc).

*i* want to do it by treating it as two annuities, finding the present value of them, and combining them.

IE: first annuity is just an increasing annuity from time 1 to n, second annuity is just a decreasing annuity from time n+1 to 2n.

HOWEVER I cannot get this to turn into the answer from the book - i'm not sure how to type these symbols into the computer either .. but take my word, I think my problem is how to 'discount' the second annuity properly to find it's present value at time 1.

Thoughts?

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