This Exam FM sample reference tests Loan Balances and Amortization. The six-month accumulation factor is 1.045, so a month-n cash flow is discounted by 1.045 to the n/6. Payment n is 500 + (n−1)X for n from 1 through 60. This timing and payment expression is choice E.
These notes identify the calculation error associated with each wrong letter when that error is reproducible.
AChoice A (30, 000 = ∑ n) does not satisfy the month-1 through month-60 timing under a six-month accumulation factor and n−1 increments; no distinct standard one-step error is identifiable.
BChoice B (30, 000 = ∑ n) does not satisfy the month-1 through month-60 timing under a six-month accumulation factor and n−1 increments; no distinct standard one-step error is identifiable.
CChoice C (30, 000 = ∑ n) does not satisfy the month-1 through month-60 timing under a six-month accumulation factor and n−1 increments; no distinct standard one-step error is identifiable.
DChoice D (30, 000 = ∑ n) does not satisfy the month-1 through month-60 timing under a six-month accumulation factor and n−1 increments; no distinct standard one-step error is identifiable.
Original practice · fully worked
Original variant: monthly payment increment required under a semiannual nominal rate
A 20,000 loan is repaid with 36 monthly payments. The first payment is 400 and each later payment is X larger. The annual nominal interest rate is 8% convertible semiannually. Calculate X.
A 11.41
B 12.09
C 12.76
D 13.43
E 14.10
Variant answer in brief
Discounting the 36 base payments and the month-index increment stream using the sixth root of 1.04 gives increment X = 13.43, choice D.
Setup
Setup
Convert the six-month factor 1.04 to an equivalent one-month factor.
q=(1.04)1/6
Model
Model
Separate the payment stream into 400 each month plus X times the index 0 through 35.
20000=400n=1∑36q−n+Xn=1∑36(n−1)q−n
Compute
Compute
The base-payment present value is 12789.21 and the increment factor is 536.994277, giving X = 13.4280.
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