The project network appeared originally as shown below, where the activity durations are indicated on each arc and ϕ designates dummy activity. After 15 days the project has been initiated, the following activities have been completed: (2,6), (2,4), (2,10). Activity (4,16) has 5 more days left; activity (6,8) has 10 days remaining; activity (8,18) has not started but its duration is re-estimated as 4 days; and all remaining activities have not yet started.

(a) Draw a new project network and evaluate the position of the company with respect to its original scheduled completion. (b) Discuss whether one has to recalculate the critical path, or could one work with the slacks on the network and make the updating? (c) Determine the precedence relationships of the original project network.