Original practice · fully worked
Original variant: final liability amount implied by a target duration
A liability pays 100 at year 1, 200 at year 3, and X at year 5. Values are discounted at 5% annually. Determine X if the liability's Macaulay duration must equal 3.5 years.
- A
220.87 - B
234.67 - C
248.48 - D
262.28 - E
276.08
Answer and calculation
Setting the time-weighted present value equal to 3.5 times total present value and isolating the year-5 amount gives X = 276.08, choice E.
Setup
Setup
Write the present-value and duration-numerator contributions of the three liabilities.
PV=100v+200v3+Xv5 N=100v+600v3+5Xv5 Model
Model
Impose the target duration by setting the numerator equal to 3.5 times present value.
100v+600v3+5Xv5=3.5(100v+200v3+Xv5) Compute
Compute
At 5%, solving the resulting linear equation gives X = 276.08.
X=276.08437500 Answer
Answer
The final liability must be 276.08, which is choice E.
X≈276.08(E)