| Exam Board | Edexcel |
|---|---|
| Module | D1 (Decision Mathematics 1) |
| Year | 2002 |
| Session | November |
| Marks | 7 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Route Inspection |
| Type | Optimal starting/finishing vertices |
| Difficulty | Standard +0.3 This is a straightforward application of the Route Inspection algorithm with a minor variation (specified start vertex). Part (a) is standard algorithm execution. Part (b) requires recognizing that with odd vertices, starting at one odd vertex means finishing at the other odd vertex to minimize repeated edges—a direct consequence of theory covered in D1. The reasoning is simple once the algorithm is understood, making this slightly easier than average. |
| Spec | 7.04e Route inspection: Chinese postman, pairing odd nodes |
\begin{enumerate}[label=(\alph*)]
\item Use the Route Inspection algorithm to find which paths, if any, need to be traversed twice.
It is decided to start the inspection at node $C$. The inspection must still traverse each pipe at least once but may finish at any node.
\item Explaining your reasoning briefly, determine the node at which the inspection should finish if the route is to be minimised. State the length of your route.\\
(3)
\end{enumerate}
\hfill \mbox{\textit{Edexcel D1 2002 Q4 [7]}}