This Exam FM sample reference tests Linking a Force of Interest to Nominal Discount. The force simplifies to 1/(10+t), so 1000 grows from time 2 to 6 by 16/12, giving X = 1333.33. Discounting this back eight quarters at 2% discount per quarter gives Y = 1134.35, choice C.
These notes identify the calculation error associated with each wrong letter when that error is reproducible.
AChoice A treats the nominal discount rate as a nominal interest rate when moving Y forward.
BChoice B uses only seven quarterly periods over the two-year interval.
DChoice D integrates the force from time zero rather than from the investment's time-2 deposit date.
EChoice E replaces the time-varying force by its value at time 2 for all four years.
Original practice · fully worked
Original variant: nominal discount rate from two accumulation paths
A 1,000 deposit grows from time 0 to time 4 under force of interest 1/(4+t). A separate 1,500 deposit must reach the same terminal amount in two years under a nominal annual discount rate d convertible semiannually. Determine d.
A 10.84%
B 12.50%
C 13.88%
D 15.25%
E 16.67%
Variant answer in brief
The force path doubles 1000 to 2000. Solving 1500 accumulated through four semiannual discount periods to 2000 gives d = 13.8790%, choice C.
Setup
Setup
Integrate the force to find the common terminal target.
F=1,000exp(∫044+tdt)=2,000
Model
Model
A semiannual nominal discount rate uses discount d divided by two each half-year.
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