Please provide a detail explanation.

Time estimates
Task ID	Task	Predecessor(s)	Most Optimistic	Most Likely	Worst Case Time
A	Obtain a building permit from county		3	15	36
B	Dig foundation and pour footers	A	5	8	24
C	Dig well for water	A	5	8	12
D	Deliver framing and roofing materials	A	3	10	15
E	Frame walls	B, D	10	15	22
F	Install septic - sewer system	A	2	5	8
G	Rough plumbing - connect water and sewer	E, C, and F	5	9	25
H	Roof building	E	10	15	33
I	Paint exterior	E	10	12	32
J	Move in manufacturing equipment	I, H, and G	18	20	30

Note: Use Pert-Mean and Pert-Std Dev values for probability computations.

Question 1. Assume that activity A took 20 days to complete. Upon completion of activity A, the project planner wants to determine the probability that project will be completed in 80 days? What is the probability?

Question 2. Assume that activity A took 20 days to complete. Activity times for B, D and F remained unchanged but activity C took 10.2 days to complete. What is the probability that project will be completed in 80 days based on project progress at the end of 30.2 days?

Question 3. Assume that activity A took 16.5 days, B 12 days, F 8 days, and E 10 days. Activity times for C and D remained unchanged. What is the probability that project will be completed in 80 days based on the project progress at the end of 38.5 days?

Question 4. Assume that activities A and B took 16.5 and 10.2 days, respectively. If activity E takes 17 days and H takes 20 days, what is the probability that project will be completed in 80 days upon completion of activity H? What should be the new activity time for activity J to have probability of completion to be .95?