Edexcel D1 2015 June — Question 1

Exam BoardEdexcel
ModuleD1 (Decision Mathematics 1)
Year2015
SessionJune
TopicCombinations & Selection

1. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{ba22b22e-c0d5-438d-821b-88619eacdb5d-2_536_476_319_434} \captionsetup{labelformat=empty} \caption{Figure 1}
\end{figure} \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{ba22b22e-c0d5-438d-821b-88619eacdb5d-2_536_474_319_1146} \captionsetup{labelformat=empty} \caption{Figure 2}
\end{figure} A delivery firm has six vans, \(\mathrm { A } , \mathrm { B } , \mathrm { C } , \mathrm { D } , \mathrm { E }\) and F , available for six deliveries, \(1,2,3,4,5\) and 6 . Each van must be assigned to just one delivery. The bipartite graph shown in Figure 1 shows the possible matchings and Figure 2 shows an initial matching. A complete matching is required, starting from the given initial matching.
  1. Explain why it is necessary to use the maximum matching algorithm twice. There are three possible alternating paths that start at either D or B . One of these is $$D - 2 = A - 3 = F - 6 = E - 5$$
  2. Find the other two alternating paths.
  3. List the improved matching generated by using the alternating path $$D - 2 = A - 3 = F - 6 = E - 5$$
  4. Starting from the improved matching found in (c), use the maximum matching algorithm to find a complete matching. You should list the alternating path that you use and your complete matching.