Independent solution

How to solve this Duration and Convexity question

Setup

Setup

Combine the two bond durations using their current prices as portfolio weights.

DP=35000(7.28)+65000(12.74)100000=10.829D_P=\frac{35000(7.28)+65000(12.74)}{100000}=10.829

Model

Model

The estimated portfolio value at the new yield follows the Macaulay yield-factor relation with that weighted duration.

105000=100000(1.04321+i)10.829105000=100000\left(\frac{1.0432}{1+i}\right)^{10.829}

Compute

Compute

Rearranging the value ratio and taking the duration root gives a new accumulation factor of about 1.0385.

1+i=1.04321.051/10.829=1.03851+i=\frac{1.0432}{1.05^{1/10.829}}=1.0385

Answer

Answer

The implied annual yield is 3.85%, which is choice C.

i=3.85%(C)\boxed{i=3.85\%\quad\text{(C)}}