| Exam Board | Edexcel |
|---|---|
| Module | D1 (Decision Mathematics 1) |
| Year | 2002 |
| Session | November |
| Marks | 6 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Critical Path Analysis |
| Type | Explain dummy activities |
| Difficulty | Moderate -0.8 This is a straightforward application of activity network construction requiring students to identify where a dummy is needed (activity E precedes both H and I/J/K, while D and F only precede H). Part (b) tests basic understanding of dummy purpose. Standard D1 bookwork with minimal problem-solving. |
| Spec | 7.05a Critical path analysis: activity on arc networks |
| Activity | Preceding activity |
| \(A\) | - |
| \(B\) | - |
| \(C\) | - |
| \(D\) | \(A\) |
| \(E\) | \(A\) |
| \(F\) | \(B\) |
| \(G\) | \(B\) |
| \(H\) | \(C , D , E , F\) |
| \(I\) | \(E\) |
| \(J\) | \(E\) |
| \(K\) | \(I\) |
| \(L\) | \(I\) |
| \(M\) | \(G , H , K\) |
2. The precedence table for activities involved in manufacturing a toy is shown below.
\begin{center}
\begin{tabular}{ | c | c | }
\hline
Activity & Preceding activity \\
\hline
$A$ & - \\
\hline
$B$ & - \\
\hline
$C$ & - \\
\hline
$D$ & $A$ \\
\hline
$E$ & $A$ \\
\hline
$F$ & $B$ \\
\hline
$G$ & $B$ \\
\hline
$H$ & $C , D , E , F$ \\
\hline
$I$ & $E$ \\
\hline
$J$ & $E$ \\
\hline
$K$ & $I$ \\
\hline
$L$ & $I$ \\
\hline
$M$ & $G , H , K$ \\
\hline
\end{tabular}
\end{center}
\begin{enumerate}[label=(\alph*)]
\item Draw an activity network, using activity on arc, and exactly one dummy, to model the manufacturing process.
\item Explain briefly why it is necessary to use a dummy in this case.
\end{enumerate}
\hfill \mbox{\textit{Edexcel D1 2002 Q2 [6]}}