This Exam FM sample reference tests Interest Rate Measures. Losing the final nine months of interest after a three-year holding leaves only 2.25 years of 8% accumulation. Equating that factor to three years at rate j gives j = 5.94%, choice B.
These notes identify the calculation error associated with each wrong letter when that error is reproducible.
AChoice A (5.74%) does not satisfy the equality of 2.25 years at 8% and three full years at the reduced rate; no distinct standard one-step error is identifiable.
CChoice C (6.14%) does not satisfy the equality of 2.25 years at 8% and three full years at the reduced rate; no distinct standard one-step error is identifiable.
DChoice D (6.34%) does not satisfy the equality of 2.25 years at 8% and three full years at the reduced rate; no distinct standard one-step error is identifiable.
EChoice E (6.54%) does not satisfy the equality of 2.25 years at 8% and three full years at the reduced rate; no distinct standard one-step error is identifiable.
Original practice · fully worked
Original variant: interest-forfeiture period implied by an equivalent reduced rate
A certificate normally earns 7% annually. If redeemed after four years, one penalty forfeits the final M months of interest; another credits 5.5% annually for all four years. Calculate M when the two penalties are equivalent.
A 9.52 months
B 10.02 months
C 10.52 months
D 11.02 months
E 11.52 months
Variant answer in brief
Equating 7% accumulation for four years minus M/12 years to four years at 5.5% and solving logarithmically gives 10.02 months, choice B.
Setup
Setup
Write the accumulation factor after forfeiting M months from the four-year original-rate term.
A1=(1.07)4−M/12
Model
Model
Set it equal to four years at the reduced annual rate.
(1.07)4−M/12=(1.055)4
Compute
Compute
Taking logarithms and isolating M gives 10.015842 months.
M=12[4−ln(1.07)4ln(1.055)]=10.01584172
Answer
Answer
The forfeited interest period is 10.02 months, selecting choice B.
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