This Exam FM sample reference tests Annuities and Perpetuities. The effective monthly rate is 0.52617%; accumulating the level 1,097 component and the five-per-month increasing component for 180 months gives 442,031, choice A.
These notes identify the calculation error associated with each wrong letter when that error is reproducible.
BChoice B is inconsistent with the level-plus-increasing monthly accumulation over 180 payments; no distinct standard single-step error producing it is identifiable.
CChoice C is inconsistent with the level-plus-increasing monthly accumulation over 180 payments; no distinct standard single-step error producing it is identifiable.
DChoice D is inconsistent with the level-plus-increasing monthly accumulation over 180 payments; no distinct standard single-step error producing it is identifiable.
EChoice E is inconsistent with the level-plus-increasing monthly accumulation over 180 payments; no distinct standard single-step error producing it is identifiable.
Original practice · fully worked
Original variant: accumulated escalating community-garden dues
A community garden contributes 200 at the end of year 1, then raises each annual contribution by 20 through year 15. At 7% effective annually, calculate the fund immediately after the year-15 contribution.
A 7,000.00
B 7,500.00
C 7,919.81
D 8,300.00
E 8,700.00
Variant answer in brief
Accumulating the 15 arithmetic payments to year 15 gives 7,919.81, choice C.
Setup
Setup
Contribution k equals 200 plus 20 times k minus one and accumulates for 15 minus k years.
A15=k=1∑15[200+20(k−1)](1.07)15−k
Model
Model
Separate the level 200 stream from the arithmetic step component.
A15=200s15∣0.07+20(Ds)15∣0.07
Compute
Compute
Evaluating both accumulated annuity parts at 7% gives 7,919.8107.
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