Using Figure 1.1: calculate the total float for activity C

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2025). The mark or mark type is shown in brackets.

1. [1] Total float is the maximum time an activity can be delayed without delaying the whole project time or LFT – duration – EST OR LST – EST
2. [2] Total float = 80 – 40 – 30.
3. [3] = 10 weeks
4. [1] Sum durations of critical path: 40 + 60 + 10 + 5 = 115 weeks
5. [1] Knowledge of CPA: network, EST, LFT, floats, nodes, minimum duration, critical path.
6. [1] Benefits of CPA: calculation of project duration
7. [1] Benefits of CPA: knowing when activities should start
8. [1] Benefits of CPA: knowing latest finish times
9. [1] Benefits of CPA: knowing critical path
10. [1] Benefits of CPA: knowing floats.
11. [1] Limitations of CPA: analysis only as good as the data.
12. [1] Limitations of CPA: new projects may not have past experience as a guide
13. [1] Limitations of CPA: planning costs.
14. [1] Limitations of CPA: does not ensure effective management.
15. [1] Knowledge of other factors: availability of finance, materials and equipment.
16. [1] Investment appraisal methods also needed to assess financial criteria for success.
17. [1] Business objectives matching project aims.
18. [1] Hard rock mine follows the hot water mine, which will be nearing completion of building and about to start production.
19. [1] Need to buy equipment for drilling and factory.
20. [1] Data for CPA from partners, suppliers and R and D.
21. [1] Minimum project duration is just over two years.
22. [1] CPA relates to the complex sequence of activities (A to H) involved in establishing the hard rock mine.
23. [1] The planned start of the mine is in two years' time (104 weeks), but the calculated duration is 115 weeks.
24. [1] CPA uses data obtained from mining industry sources and the LBM Research and Development (R&D) team.
25. [1] Lithium is found 500 metres underground.
26. [1] Activity C (Obtain drilling machinery) has 15 weeks of float.
27. [1] CPA identifies the critical activities (A-H route through nodes 1–2-4–5–7–8, for example) which, if delayed, will delay the whole project duration. This allows LBM, a new mining operator, to focus its limited resources and management supervision on these tasks, thereby preventing cost overrun.
28. [1] CPA reveals that the current duration (115 weeks) already exceeds the planned start time (2 years/104 weeks). This forces LBM to find ways to shorten the duration to meet the original target, maximising early revenue generation.
29. [1] The calculation of float (e.g., 15 weeks for activity C) enables Astor to reallocate resources away from non-critical tasks to critical ones, helping to reduce the overall project duration and improving efficiency.
30. [1] As this is the first mining activity for LBM there is no past experience to rely on therefore the data may be inaccurate.
31. [1] Supported judgement as to the importance of CPA.
32. [1] CPA is highly important for the success of the hard rock mine because the project is complex and already forecasted to be delayed (115 weeks vs 104 weeks goal). CPA provides the necessary planning and monitoring framework to potentially shorten this delay and secure timely revenue.
33. [1] CPA relies entirely on the accuracy of time estimates provided by the R&D team and suppliers. If these estimates are inaccurate (e.g., optimistic), the critical path may be wrong, leading LBM to misallocate resources and still fail to achieve the minimum duration.
34. [1] CPA must be continuously monitored and updated as the project progresses to account for unexpected operational difficulties (e.g., drilling 500m underground).
35. [1] Project success also depends on availability of finance, equipment and appropriate employees. Without them the project is less or not likely to succeed.