Edexcel D2 2002 June — Question 1 8 marks

Exam BoardEdexcel
ModuleD2 (Decision Mathematics 2)
Year2002
SessionJune
Marks8
PaperDownload PDF ↗
TopicTravelling Salesman
TypeComplete Table by Inspection
DifficultyEasy -1.2 This is a routine Decision Mathematics question requiring inspection of a small network to find shortest distances, then mechanical application of the nearest-neighbour algorithm. The network has only 6 vertices, making inspection straightforward, and the algorithm is a standard procedure requiring no problem-solving insight—just following steps methodically. This is easier than average A-level content.
Spec7.04a Shortest path: Dijkstra's algorithm7.04c Travelling salesman upper bound: nearest neighbour method

1. \begin{figure}[h]
\captionsetup{labelformat=empty} \caption{Figure 1} \includegraphics[alt={},max width=\textwidth]{c4c64221-0373-4be9-abe3-5ff281922cdb-01_675_1052_378_485}
\end{figure} Figure 1 shows a network of roads connecting six villages \(A , B , C , D , E\) and \(F\). The lengths of the roads are given in km .
  1. Complete the table in the answer booklet, in which the entries are the shortest distances between pairs of villages. You should do this by inspection. The table can now be taken to represent a complete network.
  2. Use the nearest-neighbour algorithm, starting at \(A\), on your completed table in part (a). Obtain an upper bound to the length of a tour in this complete network, which starts and finishes at \(A\) and visits every village exactly once.
    (3)
  3. Interpret your answer in part (b) in terms of the original network of roads connecting the six villages.
    (1)
  4. By choosing a different vertex as your starting point, use the nearest-neighbour algorithm to obtain a shorter tour than that found in part (b). State the tour and its length.
    (2)

1.

\begin{figure}[h]
\begin{center}
\captionsetup{labelformat=empty}
\caption{Figure 1}
  \includegraphics[alt={},max width=\textwidth]{c4c64221-0373-4be9-abe3-5ff281922cdb-01_675_1052_378_485}
\end{center}
\end{figure}

Figure 1 shows a network of roads connecting six villages $A , B , C , D , E$ and $F$. The lengths of the roads are given in km .
\begin{enumerate}[label=(\alph*)]
\item Complete the table in the answer booklet, in which the entries are the shortest distances between pairs of villages. You should do this by inspection.

The table can now be taken to represent a complete network.
\item Use the nearest-neighbour algorithm, starting at $A$, on your completed table in part (a). Obtain an upper bound to the length of a tour in this complete network, which starts and finishes at $A$ and visits every village exactly once.\\
(3)
\item Interpret your answer in part (b) in terms of the original network of roads connecting the six villages.\\
(1)
\item By choosing a different vertex as your starting point, use the nearest-neighbour algorithm to obtain a shorter tour than that found in part (b). State the tour and its length.\\
(2)
\end{enumerate}

\hfill \mbox{\textit{Edexcel D2 2002 Q1 [8]}}