Independent solution

How to solve this Arithmetic Annuity-Due question

Setup

Setup

The monthly effective rate is 0.4%, and payments at months 2k and 2k plus 1 both equal 100 plus 5k.

j=0.048/12=0.004j=0.048/12=0.004
C2k=C2k+1=100+5kC_{2k}=C_{2k+1}=100+5k

Model

Model

Factor each adjacent pair and sum over k from zero through 41.

P=(1+v)k=041(100+5k)v2kP=(1+v)\sum_{k=0}^{41}(100+5k)v^{2k}
v=(1.004)1v=(1.004)^{-1}

Compute

Compute

Evaluate the finite level and arithmetic components of the two-month series.

P=14,062.0281P=14{,}062.0281

Answer

Answer

The present value rounds to 14062, choice D.

P14,062(D)\boxed{P\approx14{,}062\quad\text{(D)}}