18.

Activity M on a CPM network has predecessors K and L, and has successor N. M has duration 5. L's late finish is 18, while K's is 20. N's late start is 14. Which of the following is definitely true?

• A. M has no slack but is not critical.
• B. The set of given times cannot all be possible
• C. M is critical and has zero slack.
• D. L is a critical activity.
• E. N is a critical activity

19.

A contractor's project being analyzed by PERT has an estimated time for the critical path of 102 days. The sum of all activity variances is 71; the sum of variances along the critical path is 58. The probability that the project will take 107 or more days to complete is

• A. 0.276
• B. 0.466
• C. 0.534
• D. 0.744
• E. 0.256

20.You have just used the network planning model and found the critical path length is 60 days and there are two critical paths. The standard deviation of the first critical path is 10 days and the standard deviation of the second critical path is 15 days. The probability that the project will be completed in 70 days or less is equal to (2 decimal accuracy)

• A. 0.16
• B. 0.75
• C. 0.25.
• D. 0.66.
• E. 0.84