4. Rob D. Store, chairperson of the Marketing Department, has made a list of all the tasks that must be completed by his staff before the end of the academic year. Given the number of days remaining in the semester, he is beginning to panic. Luckily, he has studied project management and wants to apply CPM concepts. Using the data shown, reduce the project completion time by four days. Assume a linear time-cost trade-off for each task and show, step by step, how you arrived at your schedule. Also indicate the critical path.