D1 June 2014 (R) Q3
3.
Figure 3 represents a network of roads. The number on each arc represents the time taken, in minutes, to traverse each road.
It is now necessary to include E in the route.
| Scheme | Marks |
|---|---|
| M1 A1 (SACFB) A1 (DE) A1ft (GT) | |
| Shortest path S to T: SACFDGT | A1 |
| Time of shortest path S to T is 72 (minutes) | A1ft |
| (6) |
Notes
a1M1: A larger value replaced by smaller value at least once in the working values at either D or E or F or G or T.
a1A1: All values in S, A, C, F and B correct and the working values in the correct order, including order of labelling.
a2A1: All values in D and E correct and the working values in the correct order. Penalise order of labelling only once per question.
a3A1ft: All values in G and T correct on the follow through and the working values in the correct order. Penalise order of labelling only once per question.
a4A1: CAO for the route.
a5A1ft: Follow through on their final value at T – if their answer is not 72 follow through their final value at T.
| Scheme | Marks |
|---|---|
| Shortest paths S to T including E: SACFDET | DB1 |
| Time is 75 (minutes), so 3 (minutes) longer. | B1, B1ft |
| (3) | |
| (9 marks) |
Notes
b1DB1: Must have scored the M mark in (a). Path correct.
b1B1: CAO time of new route correct.
b2B1ft: Time difference correct (ft their previous times).