| Exam Board | OCR |
|---|---|
| Module | D2 (Decision Mathematics 2) |
| Marks | 12 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Critical Path Analysis |
| Type | Identify critical path and activities |
| Difficulty | Moderate -0.8 This is a standard critical path analysis question requiring construction of an activity network and application of forward/backward scanning algorithms. While it involves multiple steps and careful bookkeeping with 13 activities, these are routine algorithmic procedures taught directly in D2 with no problem-solving insight required. The question is easier than average A-level maths because it's purely procedural application of a learned algorithm. |
| Spec | 7.05a Critical path analysis: activity on arc networks7.05b Forward and backward pass: earliest/latest times, critical activities |
| Activity | Time | Precedence |
| A | 5 | |
| B | 20 | A |
| C | 3 | A |
| D | 7 | A |
| E | 4 | B |
| F | 15 | C |
| G | 6 | C |
| H | 17 | D |
| I | 10 | F, G |
| J | 2 | G, H |
| K | 6 | E, I |
| L | 9 | I, J |
| M | 3 | K, L |
\begin{tabular}{ccc}
Activity & Time & Precedence \\
A & 5 & \\
B & 20 & A \\
C & 3 & A \\
D & 7 & A \\
E & 4 & B \\
F & 15 & C \\
G & 6 & C \\
H & 17 & D \\
I & 10 & F, G \\
J & 2 & G, H \\
K & 6 & E, I \\
L & 9 & I, J \\
M & 3 & K, L \\
\end{tabular}
Fig. 1
Construct an activity network
Use appropriate forward and backward scanning to find
\begin{enumerate}[label=(\alph*)]
\item the minimum number of days needed to complete the entire project, [3 marks]
\item the activities which lie on the critical path. [3 marks]
\end{enumerate}
[6 marks]
\hfill \mbox{\textit{OCR D2 Q2 [12]}}