PERT network?

Question

Can someone please help me find the optimistic and pessimistic times? I am lost in what is the first step to take in finding critical path.

The following represents a project with known activity times.

ACTIVITY****IMMEDIATE PREDECESSOR***TIME(in weeks)

A ****- **** 4

B **** - **** 3

C ****a**** 2

D ****b**** 7

E ***c.d*** 4

F ****b**** 5

G ***e,f *** 4

Answer 1

Just graph all steps and put task durations for each task - the longest path will be critical one.

There will be 3 paths:

X-B-F-G with duration 3+5+4=12 weeks

X-B-D-E-G with duration 3+7+4+4=18 weeks

X-A-C-E-G with duration 4+2+4+4=14 weeks

So critical path in your case will be X-B-D-E-G duration=18 weeks