Problem 3. (23 marks in total) The Lockhead Aircraft Co is ready to begin a project to develop a new fighter airplane for the US Air Force. The company's contract with the Department of Defense calls for project completion within 92 weeks, with penalties imposed for late delivery The project involves 10 activities (labeled A B...), where precedence relationship estimated completion times, and cost details are shown in the table below Time Cost Activity Precedence Relationship Normal Crash Normal Crash B D E F G 1 B B B D EG 32 weeks 28 weeks 36 weeks 16 weeks 32 weeks 54 weeks 17 weeks 20 weeks 34 weeks 18 weeks 28 weeks S160 malhon SI80 million 25 weeks S125 million $146 million 31 weeks $170 million $210 million 13 weeks S60 million $72 million 27 weeks $135 million $160 million 47 weeks $215 million $257 million 15 weeks $90 mulon $96 million 17 weeks $120 million $132 million 30 weeks $190 million $226 million 16 weeks $80 million $84 million EG CE (a) (marka) Draw the project network. Please report the earliest start the earliest finish, The latest start and the latest finisk of each activity on your diagram (b) (war Under normal circumstances, what is the completion time of the project? (c) (3 marks) What are the critical activities? Why are those activities so? (d) (2 marks) Under normal circumstances, what is the total cost of the project? (e) (10 marks) Formulate an LP model to determine an optimal crashing for each of the activities in order to complete the project within the required 92 weeks