Help me walkthrough this problem by using excel:

Analyze the probability of completing this work in 150 week span with PERT

Describe finding the expected completion times by respective activity

Predecessor Activity A Select steering committee B Develop requirements list C Develop system size estimates D Determine prospective vendors E Form evaluation team F Issue request for proposal G Bidders conference H Review submissions 1 Select vendor short list J Check vendor references K Vendor demonstrations User site visit M Select vendor N Volume sensitive test O Negotiate contracts P Cost benefit analysis Q Obtain board of directors approval A B,C,D,E F G H 1 I 1 J.KL M M NO Minimum 15 weeks 40 10 2 5 4 1 25 3 3 20 3 3 10 10 2 5 Most likely 15 weeks 45 14 2 7 5 1 30 5 3 30 3 3 13 14 2 5 Maximum 15 weeks 60 30 5 9 8 1 50 10 10 45 5 3 20 28 2 5