Given the value of z, we use the Normal Distribution appendix to find the probability that the project will be completed by time T, or sooner. An implicit assumption in this approach is that no other path will become critical during the time span of the project. Example 7.5, part (a), demonstrates this calculation for the St. John’s Hospital project.The procedure for assessing the probability of completing any activity in a project by a specific date is similar to the one just discussed. However, instead of the critical path, we would use the longest time path of activities from the start node to the activity node in question.