AS June 2025 Q2
2.
| Activity | Immediately preceding activities |
|---|---|
| A | - |
| B | - |
| C | - |
| D | B |
| E | A, B |
| F | B |
| G | B |
| H | C, D |
| I | G, H |
| J | E |
| K | E, F, I |
| L | G, H |
| M | G, H |
Each activity in the precedence table takes 3 hours to complete.
One of the activities now needs to be chosen to be extended by an hour. When the change is made the minimum completion time must not be affected.
| Scheme | Marks | AO |
|---|---|---|
| e.g. Activity D (or F or G) is preceded by activity B only, but activity E is preceded by both activity A and activity B. | B1 | 2.4 |
| (1) |
Notes
a1B1: e.g. Reference to D (or F or G) is preceded by B only, E depends on both A and B (oe).
Reference to J is preceded by E only, K depends on E and F and/or I
L and M have the same start node and finish node
| Scheme | Marks | AO |
|---|---|---|
 | M1 A1 (ABCDE) A1 (FGHJ) A1 (IKLM) A1 | 1.1b 1.1b 1.1b 1.1b 1.1b |
| (5) |
Notes
Condone lack of, or incorrect, numbered events throughout. ‘Dealt with correctly’ means that the activity starts from the correct event but need not necessarily finish at the correct event e.g. ‘K dealt with correctly’ requires the correct precedences for this activity, i.e. E, F and I labelled correctly and leading into the same node and K starting from that node but do not consider the end event for K. Activity on node is M0
If an arc is not labelled, for example, if the arc for activity E is not labelled (but the arc is present) then this will lose the first A mark and the final (CSO) A mark – they can still earn the second A mark on the bod. If two or more arcs are not labelled then mark according to the scheme. Assume that a solid line is an activity which has not been labelled rather than a dummy (even if in the correct place for where a dummy should be). Ignore incorrect or lack of arrows on the activities for the first four marks only
b1M1: At least eight activities labelled on arc, one start and at least two dummies placed.
b1A1: Activities A, B, C, D and E dealt with correctly and first dummy (from end B to end A) and arrow dealt with correctly.
b2A1: Activities F, G, H and J dealt with correctly and “second” dummy (from end E to end F) and arrow dealt with correctly.
b3A1: Activities I, K, L and M and “final” dummy and arrow dealt with correctly.
b4A1: CSO All arrows present and correctly placed with one finish, no additional dummies and no additional activities.
Please check all arcs carefully for arrows – if there are no arrows on any dummies then M1 only.
Note that additional (but unnecessary) ‘correct’ dummies that still maintain precedence for the network should only be penalised with the final A mark if earned. Note that this answer is not unique (e.g. L and M are interchangeable or this dummy could be at the start of M)
| Scheme | Marks | AO |
|---|---|---|
| 15 (hours) | B1 | 3.1b |
| (1) |
Notes
c1B1: CAO
| Scheme | Marks | AO |
|---|---|---|
| A C E F G J L M | B1 | 2.2a |
| (1) | ||
| (8 marks) |
Notes
d1B1: CAO