A company has three warehouses that supply four stores with a given product. Each warehouse has 30 units of the product. Stores 1, 2, 3, and 4 require 20, 25, 30, and 35 units of the product, respectively. The per unit shipping costs from each warehouse to each store are given in the following table. (Let X., represent the number of units that flow from warehouse i to store j for i = 1, 2, 3 and j = 1, 2, 3, 4.) Store Warehouse 1 2 3 4 1 6 5 7 7 2 5 8 5 5 3 6 5 4 3 (a) Draw the network representation of this problem. What kind of problem is this? O This is a shortest path problem. This is a transportation problem. O This is a maximal flow problem. O This is a transshipment problem. This is a minimal spanning tree problem. (c) Solve the problem using Solver. Caution: You should note that the amount of supply at the warehouses is less than the amount of demand at the stores. You will need to address this when structuring the flow balance constraints. (Hint: You want to ship everything from the warehouses even though there will be a demand shortage at the stores). (x11'x12' x 13' X 14' X 21' x 22' X 23'x24' X31 X32' X 33 X34) = *11 +12 + 15x13 +15x14+*21 +15x22 +15x23+x24+20x31 +10x32+x33+x34 (d) Suppose that shipments are not allowed between warehouse 1 and store 2 or between warehouse 2 and store 3. What is the easiest way to modify the spreadsheet so that you can solve this modified problem? Assign arbitrarily small costs such as $0.01 to the arcs representing these flows. Assign arbitrarily large costs such as $999 to the arcs representing these flows. (e) What is the optimal solution to the modified problem? (x11'x12' x 13' X 14' X 21' x 22' X 23'x24' X31 X32' X 33 X34) =