Which of the following is a primary inherent factor that directly impacts the risk, accuracy, and overall efficacy of project estimations?

In a transportation problem with total demands of 60, 40, and 50 units, and total supplies of 70 and 80 units, what is the demand required for a dummy destination to balance the problem?

For a particular project, six activities are to be carried out. The precedence relations and durations of the activities are given below: Activity A: Predecessor = None, Duration = 6 days Activity B: Predecessor = A, Duration = 5 days Activity C: Predecessor = A, Duration = 8 days Activity D: Predecessor = B, Duration = 11 days Activity E: Predecessor = C, Duration = 6 days Activity F: Predecessor = D, E, Duration = 7 days The minimum project completion time (in days) is: