| Exam Board | Edexcel |
|---|---|
| Module | D1 (Decision Mathematics 1) |
| Year | 2014 |
| Session | June |
| Marks | 7 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Critical Path Analysis |
| Type | Explain dummy activities |
| Difficulty | Moderate -0.8 This is a routine D1 question testing standard knowledge of dummy activities in activity networks. Part (a) requires mechanical construction following precedence rules, while part (b) asks for textbook explanation of why dummies are needed (to show correct dependencies without creating false ones). The question explicitly tells students to use exactly two dummies, removing any problem-solving element. This is easier than average A-level maths as it's primarily recall and application of a standard algorithm with no novel reasoning required. |
| Spec | 7.05a Critical path analysis: activity on arc networks |
| Activity | Immediately preceding activities |
| A | - |
| B | - |
| C | - |
| D | \(A , B\) |
| E | C |
| F | A, B |
| G | A, B |
| H | E, F |
| I | D |
| J | D, G |
| K | \(H\) |
2.\\
\begin{enumerate}[label=(\alph*)]
\item Draw the activity network described in the precedence table below, using activity on arc and exactly two dummies.
\begin{center}
\begin{tabular}{|l|l|}
\hline
Activity & Immediately preceding activities \\
\hline
A & - \\
\hline
B & - \\
\hline
C & - \\
\hline
D & $A , B$ \\
\hline
E & C \\
\hline
F & A, B \\
\hline
G & A, B \\
\hline
H & E, F \\
\hline
I & D \\
\hline
J & D, G \\
\hline
K & $H$ \\
\hline
\end{tabular}
\end{center}
\item Explain why each of the two dummies is necessary.\\
\end{enumerate}
\hfill \mbox{\textit{Edexcel D1 2014 Q2 [7]}}