2 sources, A and B, ship their supplies to intermediate points M and N, from which the supplies are transshipped to final destinations W, X, and Y. Source A can supply 300 units, and source B can supply 200. The costs to ship from A are $20/unit to M and $30/unit to N. The costs to ship from B are $25/unit to M and $15/unit to N. Unit shipping costs from M are $10, $5, and $15 to W, X, and Y, respectively. Unit shipping costs from N are $8, $10, and $12 to W, X, and Y, respectively. The demands at W, X, and Y are 200, 100, and 150 units, respectively.

1. Determine the optimum shipments for minimizing the total cost.
2. What is the minimum total shipping cost? Is there an alternate solution to this problem? If so, what is it?

3. If the maximum amounts that could be shipped from sources to the transshipment points were as follows: from A to M, not more than 200 units; from A to N, not more than 100 units; from B to M, not more than 150 units; and from B to N, not more than 150 units, what would be the new response?

4. If, in addition to the limits on the shipment from sources to transshipment points, the amount that could be shipped from any transshipment point to any final destination was limited to 100 units, how would your responses change to letter c?

5. If in addition to the maximum amounts that could be shipped, the cost to ship from A to M increased to $30/unit and the cost to ship from A to N decreased to $20/unit, how would your responses change to letter c?

6. Solve using Excel solver.