Edexcel D1 2018 June — Question 5 6 marks

Exam BoardEdexcel
ModuleD1 (Decision Mathematics 1)
Year2018
SessionJune
Marks6
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicMatchings and Allocation
TypeMaximum matching algorithm application
DifficultyModerate -0.5 This is a standard application of the maximum matching algorithm from D1, requiring students to work backwards from given alternating paths to deduce an initial matching, then systematically apply the algorithm. While it involves multiple steps and careful bookkeeping, it's a routine algorithmic procedure with no novel problem-solving required—slightly easier than average because the alternating paths are provided rather than needing to be discovered independently.
Spec7.02r Graph modelling: model and solve problems using graphs

5. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{6b51f3a0-0945-4254-8c63-20e1371e9e3a-06_648_567_273_750} \captionsetup{labelformat=empty} \caption{Figure 3}
\end{figure} Figure 3 shows the possible allocations of five workers, Cole (C), Dorothy (D), Harold (H), Richard (R) and Stephen (S), to five tasks, 1, 2, 3, 4 and 5. In an initial matching, each of three workers is allocated to a different task. For this initial matching, there are three possible alternating paths that start at C . One alternating path is $$C - 3 = S - 4 = D - 5$$ A second alternating path is $$\mathrm { C } - 1 = \mathrm { H } - 2$$
  1. Use this information to deduce the initial matching.
  2. Find the third alternating path that starts at C .
  3. List the improved matching generated by using the alternating path \(\mathrm { C } - 3 = \mathrm { S } - 4 = \mathrm { D } - 5\)
  4. Starting from the improved matching found in (c), use the maximum matching algorithm to obtain a complete matching. You must list the alternating path you use and the final matching.
    (3)

5.

\begin{figure}[h]
\begin{center}
  \includegraphics[alt={},max width=\textwidth]{6b51f3a0-0945-4254-8c63-20e1371e9e3a-06_648_567_273_750}
\captionsetup{labelformat=empty}
\caption{Figure 3}
\end{center}
\end{figure}

Figure 3 shows the possible allocations of five workers, Cole (C), Dorothy (D), Harold (H), Richard (R) and Stephen (S), to five tasks, 1, 2, 3, 4 and 5.

In an initial matching, each of three workers is allocated to a different task.

For this initial matching, there are three possible alternating paths that start at C .

One alternating path is

$$C - 3 = S - 4 = D - 5$$

A second alternating path is

$$\mathrm { C } - 1 = \mathrm { H } - 2$$
\begin{enumerate}[label=(\alph*)]
\item Use this information to deduce the initial matching.
\item Find the third alternating path that starts at C .
\item List the improved matching generated by using the alternating path $\mathrm { C } - 3 = \mathrm { S } - 4 = \mathrm { D } - 5$
\item Starting from the improved matching found in (c), use the maximum matching algorithm to obtain a complete matching. You must list the alternating path you use and the final matching.\\
(3)
\end{enumerate}

\hfill \mbox{\textit{Edexcel D1 2018 Q5 [6]}}