Question: For this transshipment problem, assume that there are two sources, three intermediate warehouses and two final destinations, and travel is only possible between the sources and the warehouses, and between the warehouses and all destinations. In addition, assume that no travel is possible between the sources, between the warehouses, and between destination points. Also, there is no direct travel from any of the sources to any of the final destinations. Let the source nodes be labeled as 1 and 2, the warehouses be labeled as nodes 3, 4 and 5, and the final destination points be labeled as nodes 6 and 7. If there are 800 and 500 units available at sources 1and 2 respectively, and the demands at destinations 6 and 7 are 750 and 600 units respectively, formulate a linear programming model of the problem that could be used to determine how the shipment should be made so as to minimize total cost? The shipping costs are shown in the table below.

To (Destination)

3 4 5 6 7

From (Sources)

1 4 9 10 – --

2 6 8 5 – --

3 -- -- -- 3 8

4 -- -- -- 4 7

5 -- -- -- 8 6