| Exam Board | Edexcel |
|---|---|
| Module | FD1 AS (Further Decision 1 AS) |
| Session | Specimen |
| Marks | 7 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Critical Path Analysis |
| Type | Calculate early and late times |
| Difficulty | Moderate -0.3 This is a standard Critical Path Analysis question requiring construction of an activity network and calculation of early/late times. While it involves multiple steps and careful bookkeeping, it follows a completely algorithmic procedure taught directly in the syllabus with no problem-solving insight required. The presence of dummy activities adds minor complexity, but this is routine for CPA questions. |
| Spec | 7.05a Critical path analysis: activity on arc networks7.05b Forward and backward pass: earliest/latest times, critical activities7.05c Total float: calculation and interpretation |
| Activity | Time taken (days) | Immediately preceding activities |
| A | 5 | - |
| B | 7 | - |
| C | 3 | - |
| D | 4 | A, B |
| E | 4 | D |
| F | 2 | B |
| G | 4 | B |
| H | 5 | C, G |
| I | 10 | C, G |
| Answer | Marks | Guidance |
|---|---|---|
| Answer/Working | Mark | Guidance |
| Network diagram: at least 5 activities and one dummy, one start | M1 | |
| A, B, C, D, F, G and first dummy correct | A1 | |
| E, H, I correct, second dummy correct and one finish | A1 | |
| All boxes completed, numbers generally increasing L to R (condone one "rogue") | M1 | |
| All values cao | A1 | |
| Deduction that result in diagram indicates project can be completed in 21 days | A1ft | All boxes completed, numbers generally increasing in direction of arrows for top boxes and generally decreasing in opposite direction for bottom boxes |
| Critical activities: B, G, I | A1 | Critical activities correct |
## Question 3(a)(b):
| Answer/Working | Mark | Guidance |
|---|---|---|
| Network diagram: at least 5 activities and one dummy, one start | M1 | |
| A, B, C, D, F, G and first dummy correct | A1 | |
| E, H, I correct, second dummy correct and one finish | A1 | |
| All boxes completed, numbers generally increasing L to R (condone one "rogue") | M1 | |
| All values cao | A1 | |
| Deduction that result in diagram indicates project can be completed in 21 days | A1ft | All boxes completed, numbers generally increasing in direction of arrows for top boxes and generally decreasing in opposite direction for bottom boxes |
| Critical activities: B, G, I | A1 | Critical activities correct |
---3.
\begin{center}
\begin{tabular}{|l|l|l|}
\hline
Activity & Time taken (days) & Immediately preceding activities \\
\hline
A & 5 & - \\
\hline
B & 7 & - \\
\hline
C & 3 & - \\
\hline
D & 4 & A, B \\
\hline
E & 4 & D \\
\hline
F & 2 & B \\
\hline
G & 4 & B \\
\hline
H & 5 & C, G \\
\hline
I & 10 & C, G \\
\hline
\end{tabular}
\end{center}
The table above shows the activities required for the completion of a building project. For each activity, the table shows the time taken in days to complete the activity and the immediately preceding activities. Each activity requires one worker. The project is to be completed in the shortest possible time.
\begin{enumerate}[label=(\alph*)]
\item Draw the activity network described in the table, using activity on arc. Your activity network must contain the minimum number of dummies only.
\item \begin{enumerate}[label=(\roman*)]
\item Show that the project can be completed in 21 days, showing your working.
\item Identify the critical activities.
\end{enumerate}\end{enumerate}
\hfill \mbox{\textit{Edexcel FD1 AS Q3 [7]}}