What is meant by the term "slack" as applied to a particular activity? What is the difference between positive and negative slack? How is it calculated? 2) Which of the following is not a measure of dispersion, or spread, of a distribution: variance, mean, or standard deviation? 3) The earliest expected finish time for a project is 138 days, and its required completion time is 130 days, What is the probability of completing the project before its required time if the standard deviation of the total distribution of the activities on the longest path is 6?