Consider the following project network:

For each activity, the pessimistic, optimistic, and most likely task duration has been defined as follows:

Activity	Pessimistic Estimate	Optimistic Estimate	Most Likely	E[t]	s
1-2	18	14	16
1-3	16	11	14
2-6	23	13	18
3-4	9	7	8
3-5	16	16	16
2-5	37	20	26
4-8	12	6	8
5-7	13	8	10
6-7	15	6	8
7-8	4	3	1

1. Find the expected value and standard deviation for each activity time. What distribution does each of these time estimates follow?
2. Find the critical path for the project. (Assume activity 1-2 starts at time 0).
3. Compute the expected value and the standard deviation of completion time for the critical path. What distribution does this time estimate follow?
4. The project contract specifies that the project will be done in 50 days. What is the probability that this completion time will be achieved?