Activity		Description	Immediate Predecessor		Optimistic (weeks)	Most Probable (weeks)	Pessimistic (weeks)
A	Build Internal Component			-	4	5	6
B	Modify roof and floor			-	3	6	9
C	Construct collection stack			-	9	10	11
D	Pour concrete and install frame			A,B,C	12	13	14
E	Build high temperature burner			A	4	8	12
F	Install control system			D	4	5	6
G	Install air pollution device			D	1	4	7

Required:

1. Calculate the expected time for each activity
2. Construct the network diagram
3. Calculate earliest start and finish times and latest start and finish times for the project.
4. Determine the critical path for the project
5. Determine the variance for the project
6. Determine the probability that the project will be finished in (i) 12 days or less (ii) more than 12 days (iii) 20 days or more.