Question 4 (25 marks) (a) The activities involved in an Aero-engine assembly project are given below in Table 4.1. Apply the activity-on-arrow methodology to determine: (i) The critical path network diagram for this project. (8 marks) (ii) The critical path(s). (2 marks) (iii) The project completion time. (2 marks) (iv) The slack time for all non-critical activities. (7 marks) Table 4.1 Activity Immediate Duration predecessors (days) The Main Frame Body A 15 B A 5 B 6 D 3 E B 5 F B 10 G F 3 H GU 2 I D, E, H 1 J I 2 The Main Engine K L M N L, O M, U bx* O OZZ 10 10 5 2 5 6 1 1 2 Q R S N, P, Q General activities U V T J, S 10 8 5 (b) Briefly discuss the application of Standard Deviation in the project management. With reference to part (a), assuming the standard deviation of all the activities is 1 day, what will be the probability of the project completion day is 45 days? (6 marks)