Independent solution

How to solve this Cash-Flow and Risk Matching question

Setup

Setup

A maturity pair can match duration 15.24 only if one maturity lies below and one lies above it, so a 20-year zero is necessary.

x+z=9697,5x+20z=15.24(9697)x+z=9697,\qquad 5x+20z=15.24(9697)

Model

Model

For the 5- and 20-year pair, solve the current-value total and the duration numerator simultaneously.

x=3077.18,z=6619.82x=3077.18,\qquad z=6619.82

Compute

Compute

The resulting allocation matches both targets and has convexity 281.00. The 15- and 20-year alternative has convexity only 233.40.

CA=52x+202z9697=281.00>242.47C_A=\frac{5^2x+20^2z}{9697}=281.00>242.47

Answer

Answer

Only the 5/20 allocation satisfies the Redington convexity inequality, giving choice A.

(3077, 6620)(A)\boxed{(3077,\ 6620)\quad\text{(A)}}