D1 June 2013 Q4
4.
Figure 3 represents a network of roads. The number on each arc represents the length, in miles, of the corresponding road. Liz wishes to travel from S to T.
On a particular day, Liz must include F in her route.
| Scheme | Marks |
|---|---|
 | M1 A1 (A,B,C,D) A1 (E,F,G) A1ft(H and T) |
| Shortest path S to T: SADGEHT | A1 |
| Length of shortest path S to T: 30 (miles) | A1ft |
| (6) |
Notes
a1M1 A larger value replaced by a smaller value at least once in the working values at either B or E or F or H or T.
a1A1 All values in A, B, C and D correct. The working values at B must be in the correct order.
a2A1 All values in E, F and G correct and the working values in the correct order. Penalise order of labelling only once per question (F, G and E labelled in that order and F must be labelled after A, B, C and D).
a3A1ft All values in H and T ft correct and the working values in the correct order. Penalise order of labelling only once per question (H and T labelled in that order and H labelled after all other nodes).
a4A1 Route CAO.
a5A1ft ft on their final value (if answer is not 30 ft their final value at T).
| Scheme | Marks |
|---|---|
| Shortest path S to T via F: SCBFEHT | B1 |
| Length is 31 (miles) | B1 |
| (2) | |
| (8 marks) |
Notes
b1B1 Route CAO
b2B1 Length CAO (condone lack of (or incorrect) units throughout).