Consider the revised Coal Bank Hollow recycling problem discussed in section 5.5.4 of this chapter. We said that it is safest to assume the supply in a generalized network flow problem is capable of meeting the demand (until Solver proves otherwise).

a. Solve the problem in Figure (a) (and file Fig (a).xls on your data disk) assuming 80 tons of newspaper is available and that the supply is NOT adequate to meet the demand. How much of each of the raw recycling materials is used? How much demand for each product is met? What is the cost of this solution?

b. Solve the problem again assuming that the supply is adequate to meet the demand. How much of each of the raw recycling materials is used? How much demand for each product is met? What is the cost of this solution?

c. Which one is better? Why?

d. Suppose there are 55 tons of newspaper available. Figure (b) shows the least cost solution for distributing the supply in this case. In that solution, the demand for newsprint pulp and packaging pulp is met but we are almost 15 tons short on print stock pulp. How much can this shortage be reduced (without creating shortages of the other products) and how much extra would it cost to do so?

Figure (a)

Figure(b)

Fig5-17xls (Compstibility Model -Microsoft Excel Home Insert Page LayoutFormulas Data ReviewViewAdd-Ins M6 Coal Bank Hollow Recycling 5 Flow From Node Cost Node 1 Newspaper 2 Mixed Paper Net Flow SupplyiDemand 01 Newspaper 0.0 5 Proces5 1 46.8 6 Process 40.0 5 Process 1 0.0 6 Proce3s 2 28.5 5 Process 0.0 6 Process 30.0 5 Process 1 0.0 6 Process 2 51.4 7 Newsprint 40.0 8Fackaging 00 9 Print Stock 8.6 7 Newsprint 0.0 8 Packaging 55.01 Newspaper0.85 B 50.0 2 Mixed Paper 3 White Ofmice 30.0 0 2 Mixed Paper0.85 0.95 0.90 4 Cardboard Process 1 Process 2 T Newsprint 8 Packaging 40 10 30.0 3 White Office | 11 0.0 3 White Office 12 40.0 4 Cardboard 13.4 Cardboard 14 54.1 5 Process 1 $14 15 5 Process 1 0.0 5 Process 1 17 9.6 6 Proces3 2 18 0.0 6 Process 2 19 37.1 6 Process $8 20.95 353 9 Print Stock S7 Total Cost $2,955