AQA D1 2006 June — Question 4 11 marks

Exam BoardAQA
ModuleD1 (Decision Mathematics 1)
Year2006
SessionJune
Marks11
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicRoute Inspection
TypeChinese Postman with flexible endpoints
DifficultyStandard +0.8 This is a multi-part Chinese Postman problem requiring students to handle three variations: standard (return to start), flexible endpoint, and completely flexible start/finish. Part (a) is routine, but parts (b) and (c) require understanding how odd vertices affect optimal routes and selecting appropriate pairings—this demands genuine problem-solving beyond algorithm recall, placing it moderately above average difficulty.
Spec7.04e Route inspection: Chinese postman, pairing odd nodes

4 The diagram shows a network of roads connecting 6 villages. The number on each edge is the length, in miles, of the road. \includegraphics[max width=\textwidth, alt={}, center]{63e7775d-2a63-4584-b3be-ce97927bcfcc-04_670_1298_466_356} Total length of the roads \(= 164\) miles
  1. A police patrol car based at village \(A\) has to travel along each road at least once before returning to \(A\). Find the length of an optimal 'Chinese postman' route for the police patrol car.
  2. A council worker starts from \(A\) and travels along each road at least once before finishing at \(C\). Find the length of an optimal route for the council worker.
  3. A politician is to travel along all the roads at least once. He can start his journey at any village and can finish his journey at any village.
    1. Find the length of an optimal route for the politician.
    2. State the vertices from which the politician could start in order to achieve this optimal route.

4 The diagram shows a network of roads connecting 6 villages. The number on each edge is the length, in miles, of the road.\\
\includegraphics[max width=\textwidth, alt={}, center]{63e7775d-2a63-4584-b3be-ce97927bcfcc-04_670_1298_466_356}

Total length of the roads $= 164$ miles
\begin{enumerate}[label=(\alph*)]
\item A police patrol car based at village $A$ has to travel along each road at least once before returning to $A$. Find the length of an optimal 'Chinese postman' route for the police patrol car.
\item A council worker starts from $A$ and travels along each road at least once before finishing at $C$. Find the length of an optimal route for the council worker.
\item A politician is to travel along all the roads at least once. He can start his journey at any village and can finish his journey at any village.
\begin{enumerate}[label=(\roman*)]
\item Find the length of an optimal route for the politician.
\item State the vertices from which the politician could start in order to achieve this optimal route.
\end{enumerate}\end{enumerate}

\hfill \mbox{\textit{AQA D1 2006 Q4 [11]}}