Activity D has an optimistic time of three days, a pessimistic time of nine days, and a most likely time of four days. Determine its expected time and variance.
Activity E has an optimistic time of 9 days, a most likely time of 12 days, and a pessimistic time of 15 days. Estimate its expected time and standard deviation.
Activity J has a duration of 7 and an earliest finish time of 21. If J's latest start time is 16, this must mean that J's slack is: