This Exam FM sample reference tests Duration and Convexity. The annuity present value is 78.1729X and its time-weighted present value is 2,178.3542X; their ratio gives Macaulay duration 27.87 years, choice B.
These notes identify the calculation error associated with each wrong letter when that error is reproducible.
AChoice A is inconsistent with the two-block ordinary and time-weighted present values; no distinct standard single-step error producing it is identifiable.
CChoice C is inconsistent with the two-block ordinary and time-weighted present values; no distinct standard single-step error producing it is identifiable.
DChoice D is inconsistent with the two-block ordinary and time-weighted present values; no distinct standard single-step error producing it is identifiable.
EChoice E is inconsistent with the two-block ordinary and time-weighted present values; no distinct standard single-step error producing it is identifiable.
Original practice · fully worked
Original variant: duration of a two-tier public-media subsidy
A subsidy pays 100 at the beginnings of years 1–10 and 300 at the beginnings of years 11–20. At 4% effective annually, calculate its Macaulay duration at time zero.
A 9.50
B 10.20
C 10.87
D 11.50
E 12.00
Variant answer in brief
The 20 dated present-value weights have mean payment time 10.873 years, choice C.
Setup
Setup
Beginning-of-year timing places the first subsidy at time zero and the last at time 19.
PV=t=0∑9100vt+t=10∑19300vt=2553.1155
Model
Model
Discount both tiers and use calendar time, not a restarted index, in the duration numerator.
M1=t=0∑9100tvt+t=10∑19300tvt
Compute
Compute
The ordinary value is 2,553.1155 and their weighted mean time is 10.87333.
DM=M1/PV=10.87333
Answer
Answer
The Macaulay duration is 10.87 years, which is choice C.
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