a. Construct the network diagram. b. Indicate the critical path when normal activity times are used. c. Compute the minimum total direct cost for each project duration based on the cost associated with each activity. Consider durations of 13, 14, 15, 16, 17, and 18 weeks. d. If the indirect costs for each project duration are $ 400 (18 weeks), $ 350 ( 17 weeks), $ 300 ( 16 weeks), $ 250 ( 15 weeks), $ 200 ( 14 weeks), and $ 150 ( 13 weeks), what is the total project cost for each duration? Indicate the minimum total project costduration.