Problem 3 [25 pts] You are the leader of a team to solve a transportation problem for a client, who wants cost minimization with a 6-node topology. Supply in Nodes 1 and 2 (of 160 and 200 daily units, respectively), and Demand in Nodes 5 and 6 {of 140 daily units in both nodes). Nodes 3 and 4 can be used for transshipment, but do not have any Supply or Demand. The structure of the network and the shipment costs between any pair of nodes are shown in Figure 2. Figure 2: Network for Problem 3 a. Formulate the problem as a network ow problem. Please dene your decision variables, objective and constraints. [8 pts] b. Implement the problem in a spreadsheet. Please include screenshots of the spreadsheet and the solver setting to show how you work. [8 pts] c. Report the optimal transportation solution and the total cost. [5 pts] d. Suppose that after you run solver, the spreadsheet gives you non-integer results. You will make a recommendation to your client, who has no knowledge of linear programs or optimization. Among the actions below (A to E), which should you do? Why? [4 pts] - A: Report the non-integer values because that is the optimal solution to the linear program. 0 B: Add constraints forcing all variables to be integer valued, and run solver again. 0 0: Round each variable down, because at least that will always be feasible. 0 D: Round some of the variables up and some of them down, looking for a feasible solution. 0 E: Check the problem implementation in spreadsheet, because there must be some errors