Independent solution

How to solve this Annuities question

Setup

Setup

Deposit k has amount X times 1.03 to the k minus 1 and accumulates from year k to year 15.

Dk=X(1.03)k1D_k=X(1.03)^{k-1}
F15=k=115Dk(1.08)15kF_{15}=\sum_{k=1}^{15}D_k(1.08)^{15-k}

Model

Model

Factor out X from the finite geometric accumulation sum.

2000=Xk=115(1.03)k1(1.08)15k2000=X\sum_{k=1}^{15}(1.03)^{k-1}(1.08)^{15-k}

Compute

Compute

The accumulation factor is 32.28403395, giving X = 61.950127.

X=61.95012689X=61.95012689

Answer

Answer

The first deposit is approximately 62, selecting choice C.

X62(C)\boxed{X\approx62\quad\text{(C)}}