This Exam FM sample reference tests Loan Amortization. For a level-payment loan, principal portions grow by one plus the monthly rate; over 24 months the factor is (1.10)², so the 30th principal portion is 500(1.10)² = 605, choice C.
These notes identify the calculation error associated with each wrong letter when that error is reproducible.
AChoice A is inconsistent with the principal-portion geometric progression; no distinct standard single-step error producing it is identifiable.
BChoice B is inconsistent with the principal-portion geometric progression; no distinct standard single-step error producing it is identifiable.
DChoice D is inconsistent with the principal-portion geometric progression; no distinct standard single-step error producing it is identifiable.
EChoice E is inconsistent with the principal-portion geometric progression; no distinct standard single-step error producing it is identifiable.
Original practice · fully worked
Original variant: infer a loan rate from principal growth
A gallery mortgage has level monthly payments. The principal portions of payments 10 and 34 are 300 and 376.32, respectively. Determine the annual effective interest rate.
A 8.00%
B 10.00%
C 12.00%
D 14.00%
E 16.00%
Variant answer in brief
Principal grows by 1.2544 over two years, so the annual effective factor is its square root, giving 12%, choice C.
Setup
Setup
Successive principal portions in a level-payment schedule grow at the monthly loan factor.
P10P34=(1+j)24=300376.32=1.2544
Model
Model
The two observed portions are 24 months, or two annual effective periods, apart.
(1+iannual)2=1.2544
Compute
Compute
Their ratio is 1.2544, whose two-year annual-factor root is 1.12.
iannual=1.2544−1=0.12
Answer
Answer
The annual effective interest rate is 12.00%, corresponding to choice C.
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