| Exam Board | OCR |
|---|---|
| Module | D2 (Decision Mathematics 2) |
| Year | 2013 |
| Session | January |
| Marks | 12 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Critical Path Analysis |
| Type | Effect of activity delay/change |
| Difficulty | Moderate -0.5 This is a standard Critical Path Analysis question requiring routine application of forward/backward pass algorithms and float calculations. While multi-part with several steps, all techniques are textbook procedures with no novel problem-solving required. Part (iii) tests understanding of total float, parts (iv-v) test understanding of how delays affect critical vs non-critical activities—all standard D2 content that's slightly easier than average A-level due to being algorithmic rather than requiring mathematical insight. |
| 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 interpretation7.05d Latest start and earliest finish: independent and interfering float |
I cannot identify a mark scheme in the provided content. The text appears to be:
- A data table showing days of the week and number of playhouses
- A footer section containing copyright information and OCR branding
There are no marking annotations (M1, A1, B1, DM1, etc), no marking points, and no assessment criteria visible in this extract.
Please provide the actual mark scheme content for Question 2.2 A project is represented by this activity network. The weights (in brackets) on the arcs represent activity durations, in minutes.\\
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(i) Complete the table in the answer book to show the immediate predecessors for each activity.\\
(ii) Carry out a forward pass and a backward pass through the activity network, showing the early event time and the late event time at each vertex of your network. State the minimum project completion time and list the critical activities.
Suppose that the start of one activity is delayed by 2 minutes.\\
(iii) List each activity which could be delayed by 2 minutes with no change to the minimum project completion time.\\
(iv) Without altering your diagram from part (ii), state the effect that a delay of 2 minutes on activity $A$ would have on the minimum project completion time. Name another activity which could be delayed by 2 minutes, instead of $A$, and have the same effect on the minimum project completion time.\\
(v) Without altering your diagram from part (ii), state what effect a delay of 2 minutes on activity $C$ would have on the minimum project completion time.
\hfill \mbox{\textit{OCR D2 2013 Q2 [12]}}