21. The following table provides the information necessary to construct a project network and project crash data: Activity (i,j) ActivityActivity Time (weeks) Activity Cost Normal $2000 1000 500 600 1500 800 3000 5000 Predecessor Normal Crash Crash 16 14 (2,4) (2,5) (3,5) (3,6) (4,6) 5,6 $4400 1800 700 1300 3000 1600 4500 8000 4 10 15 10 a. Construct the project network, and determine its completion time and critical path b. Manually crash the network based on the above information, and determine the valueS: 1) the completion time 2) critical path(s) 3) total crashed cost 4) total crashed days