Avianunca Aircraft Company is preparing a contract proposal for a new passenger aircraft. Part of the proposal is a development and production schedule for completion of the first aircraft. The project consists of three primary categories: engine design and development, development and production of the airframe, and design and development of the aircraft avionics. Following is a list of the project activities, with time estimates (in months): Most Optimistic Likely Pessimistic Time Time Time Activity Estimate Estimate Estimate Activity Description Predecessor (a) (m) (b) 1 General design 5 10 22 2 Engine design - 20 33 57 3 Airframe design 1 6 17 33 4 Avionics design 1 2 8 20 5 Develop test engine 2 7 10 12 6 Develop test airframe 3 8 11 18 7 Develop interim avionics 4 7 15 28 8 Develop engine 2 19 24 41 9 Assemble test aircraft 5, 6, 7 4 6 10 10 Test avionics 4 5 10 16 k Engine/airframe flight trials 9 9 12 12 Avionics flight trials 10 5 9 24 13 Produce engine 8 11 14 15 14 Produce airframe 11 12 15 20 O Produce avionics 11, 12 14 16 25 p Final assembly 13, 14, 15 2 3 5 a) Develop the project network, determine the critical path, determine the expected project duration and the project variance. b) What is the probability that the project will be completed within 8 years