Independent solution

How to solve this Annuities and Perpetuities question

Setup

Setup

Start with an indefinitely increasing payment sequence.

(Ia)∞=1+ii2=134.5679(Ia)_\infty=\frac{1+i}{i^2}=134.5679

Model

Model

Subtract two increasing sequences beginning after the peak to reverse the slope, then add one later sequence to stop the decline at five.

X=(Ia)∞−2v10(Ia)∞+v15(Ia)∞X=(Ia)_\infty-2v^{10}(Ia)_\infty+v^{15}(Ia)_\infty

Compute

Compute

All three components share the increasing-perpetuity factor and differ only by their shifts.

X=134.5679(1−2v10+v15)=57.83X=134.5679(1-2v^{10}+v^{15})=57.83

Answer

Answer

The present value is 57.83, nearest choice D.

X≈58(D)\boxed{X\approx58\quad\text{(D)}}