Independent solution

How to solve this Annuities and Perpetuities question

Setup

Setup

Each beginning-of-year deposit remains principal; at each year-end, simple interest on all deposited principal is transferred.

V10=10X+k=110(0.12kX)(1.08)10kV_{10}=10X+\sum_{k=1}^{10}(0.12kX)(1.08)^{10-k}

Model

Model

The transferred interest amounts form an increasing sequence and then earn 8% for their remaining times.

V10=18.4683XV_{10}=18.4683X

Compute

Compute

Adding the 10 units of principal and all accumulated transfers gives 18.4683 units of final value per unit deposit.

X=1000018.4683=541.47X=\frac{10000}{18.4683}=541.47

Answer

Answer

The required beginning-of-year deposit is 541.47, corresponding to choice B.

X=541.47(B)\boxed{X=541.47\quad\text{(B)}}