Original practice · fully worked
Original variant: infer duration from an estimated price
A conservation note is worth 2,000 at 4% annual effective yield. Under the Macaulay yield-factor approximation, its estimated value at 4.5% is 1,943.27. Determine the Macaulay duration used.
- A
4.0 - B
5.0 - C
6.0 - D
7.0 - E
8.0
Answer and calculation
Taking logarithms of the price ratio and yield-factor ratio gives Macaulay duration 6.0, choice C.
Setup
Setup
Divide the estimated new value by the original value to obtain the observed price factor.
20001943.27=(1.0451.04)DM Model
Model
The Macaulay approximation raises the old-to-new yield factor to the unknown duration.
DM=log(1.04/1.045)log(1943.27/2000) Compute
Compute
Taking logarithms isolates the exponent and gives 5.9999.
DM=5.9999 Answer
Answer
The Macaulay duration is 6.0 years, corresponding to choice C.
DM≈6.0(C)