6.2. *Consider the transportation problem having the unit shipping costs shown in the following table. Destination 1 2 3 Supply Source 1 2 6 5 7 8 4 6 40 60 Demand 30 40 30 Formulate a network model for this problem as a minimum-cost flow problem by drawing a network similar to Figure 6.3. b. Formulate and a spreadsheet model for this problem. 6.3. Reconsider Problem 6.2. Suppose now that the demand at each of the destinations has been reduced by 10, so that the new demands are 20,30, and 20 at destinations 1, 2, and 3, respectively. Introduce a dummy destination in order to satisfy the feasible solutions property and then repeat parts a and b to determine how much each source should supply to each destination for this new version of the problem a Formulate and a spreadsheet model for this problem without introducing a dummy destination. b. Now convert this problem into a minimum-flow cost flow problem by introducing a dummy destination and making the other needed adjustments. Then draw a network similar to Figure 6.3 for this minimum-cost flow problem.) Formulate and a spreadsheet model for the minimum-cost flow problem obtained in part 1. Then compare the resulting optimal flow plan (while ignoring the flows into the dummy destination) with the optimal flow plan obtained in part a without using a dummy destination C