| Exam Board | Edexcel |
|---|---|
| Module | D1 (Decision Mathematics 1) |
| Marks | 7 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Critical Path Analysis |
| Type | Explain dummy activities |
| Difficulty | Moderate -0.5 This is a standard D1 precedence table question requiring students to draw an activity network with dummy activities and explain their purpose. While it requires understanding of dummy activities (a key D1 concept), the question is routine and follows a well-practiced procedure. The explanation in part (b) is straightforward once the network is correctly drawn. Slightly easier than average due to being a standard textbook-style exercise with clear instructions. |
| Spec | 7.05a Critical path analysis: activity on arc networks |
| Activity | Immediately preceding activity |
| A | - |
| B | \(\boldsymbol { A }\) |
| \(\boldsymbol { C }\) | \(\boldsymbol { A }\) |
| D | A |
| E | \(\boldsymbol { B } \boldsymbol { C }\) |
| F | B C |
| G | \(\boldsymbol { D }\) |
| \(\boldsymbol { H }\) | D |
| I | E |
| \(J\) | E F \(G\) |
| \(K\) | E F \(G\) |
| \(\boldsymbol { L }\) | I J |
5.
\begin{center}
\begin{tabular}{|l|l|}
\hline
Activity & Immediately preceding activity \\
\hline
A & - \\
\hline
B & $\boldsymbol { A }$ \\
\hline
$\boldsymbol { C }$ & $\boldsymbol { A }$ \\
\hline
D & A \\
\hline
E & $\boldsymbol { B } \boldsymbol { C }$ \\
\hline
F & B C \\
\hline
G & $\boldsymbol { D }$ \\
\hline
$\boldsymbol { H }$ & D \\
\hline
I & E \\
\hline
$J$ & E F $G$ \\
\hline
$K$ & E F $G$ \\
\hline
$\boldsymbol { L }$ & I J \\
\hline
\end{tabular}
\end{center}
The precedence table shows the activities involved in planning an opening ceremony. An activity on arc network is to be drawn to model this planning process.
\begin{enumerate}[label=(\alph*)]
\item Draw the activity network using exactly two dummies.
\item Explain why each of the two dummies is necessary.
\end{enumerate}
\hfill \mbox{\textit{Edexcel D1 Q5 [7]}}