Edexcel D1 2005 January — Question 5

Exam BoardEdexcel
ModuleD1 (Decision Mathematics 1)
Year2005
SessionJanuary
TopicShortest Path

5. \begin{figure}[h]
\captionsetup{labelformat=empty} \caption{Figure 3} \includegraphics[alt={},max width=\textwidth]{e64b50bc-13a3-4051-b8c1-d4e7ea49e3a5-5_590_1360_1265_331}
\end{figure} Figure 3 shows a network of paths. The number on each arc gives the distance, in metres, of that path.
  1. Use Dijkstra's algorithm to find the shortest distance from \(A\) to \(H\).
    (5)
  2. Solve the route inspection problem for the network shown in Figure 3. You should make your method and working clear. State a shortest route, starting at \(A\), and find its length.
    [0pt] [The total weight of the network is 1241]
    (6) \begin{figure}[h]
    \captionsetup{labelformat=empty} \caption{Figure 4} \includegraphics[alt={},max width=\textwidth]{e64b50bc-13a3-4051-b8c1-d4e7ea49e3a5-6_634_1486_301_312}
    \end{figure} Figure 4 shows a capacitated directed network. The number on each arc is its capacity.
    (a) State the maximum flow along
  3. SADT,
  4. SCET,
  5. \(S B F T\).
    (b) Show these maximum flows on Diagram 1 in the answer book. Take your answer to part (b) as the initial flow pattern.
    (c) (i) Use the labelling procedure to find a maximum flow from \(S\) to \(T\). Your working should be shown on Diagram 2 in the answer book. List each flow-augmenting route you use, together with its flow.
  6. Draw your final flow pattern on Diagram 3 in the answer book.
  7. Prove that your flow is maximal.
    (d) Give an example of a practical situation that could have been modelled by the original network.