please answer this correctly. the other answer on this site was wrong

13.15 A hospital is planning to add a $ 60 million patient tower. To support both the existing hospital facility and the new patient tower, an existing energy plant will be expanded and upgraded. Equipment upgrades include a new generator, liquid oxygen tanks, cooling towers, boilers, and a chiller system to ensure adequate electricity, heating, air-conditioning, hot water, and oxygen delivery systems. Existing fuel tanks will be relocated. The activities, their immediate predecessors, and the optimistic, most likely, and pessimistic times in weeks for this project are listed in Table EX 13.15. Table EX 13.15 19 Activity Activity Predecessor Optimistic Most Pessimis Name Likely A Design 14 15 17 B Budget A 2 3 Estimate C Permits B 14 16 D Bid Process C 7 8 9 E Subcontractor D 4 5 7 Buyout F Start-Up E 3 G New F 22 24 Additional Construction Cooling 20 24 Tower Procurement Cooling GH 11 12 4 5 18 H 22 9 Tower Installation LOX/Fuel Tank J I 1 1 3 K 29 30 31 Boiler Procurement L J,K 19 31 34 Boiler Installation Abate Old Boiler M L 1 1 1 3 N 28 30 32 O M, N 25 29 34 P 2 8 30 31 Chiller Procurement Chiller Installation Generator Procurement Generator Installation Final Inspection/ Testing Q P 12 16 1 20 R O, Q 1 1 1 N a. Calculate the mean duration time for each activity. b. Calculate the variance for each activity time. c. Identify the mean and the standard deviation for each path. d. Calculate project completion probability for 147, 150, and 152 weeks