D1 June 2009 Q8
8.
A construction project is modelled by the activity network shown in Figure 5. The activities are represented by the arcs. The number in brackets on each arc gives the time, in days, to complete the activity. Each activity requires one worker. The project is to be completed in the shortest possible time.
(a) Complete Diagram 2 in the answer book, showing the early and late event times. (4)
(b) State the critical activities. (1)
(c) Find the total float for activities M and H. You must make the numbers you use in your calculations clear. (3)
(d) On the grid provided, draw a cascade (Gantt) chart for this project. (4)
An inspector visits the project at 1pm on days 16 and 31 to check the progress of the work.
(e) Given that the project is on schedule, which activities must be happening on each of these days? (3)
| Scheme | Marks |
|---|---|
 | M1 A1 M1 A1 |
| (4) |
| Scheme | Marks |
|---|---|
| A C J L | B1 |
| (1) |
| Scheme | Marks |
|---|---|
| Total float for M = 56(ft) – 46 – 9 = 1 | M1 A1ft |
| Total float for H = 47 – 12 – 21 = 14 | B1 |
| (3) |
| Scheme | Marks |
|---|---|
 | M1 A1 M1, A1 |
| (4) |
| Scheme | Marks |
|---|---|
| 1pm day 16: C | B1ft |
| 1pm day 31: C F G H | B2ft, 1ft, 0 |
| (3) | |
| (15 marks) |