A paper recycling company converts newspaper, mixed paper, white office paper, and cardboard into pulp for newsprint, packaging paper, and print stock quality paper. The following table summarizes the yield for each kind of pulp recovered from each ton of recycled material.

Recycling Yield

Newsprint Packaging Print Stock

Newspaper 85% 80% ____

Mixed Paper 90% 80% 70%

White Office Paper 90% 85% 80%

Cardboard 80% 70% ___

For instance, a ton of newspapers can be recycled using a technique that yields 0.85 tons of newsprint pulp. Alternatively, a ton of newspapers can be recycled using a technique that yields 0.80 tons of packaging paper. Similarly, a ton of cardboard can be recycled to yield 0.80 tons of newsprint or 0.70 tons of packaging paper pulp.

Note that newspaper and cardboard cannot be converted to print stock pulp using

the techniques available to the recycler.

The cost of processing each ton of raw material into the various types of pulp is summarized in the following table along with the amount of each of the four raw materials that can be purchased and their costs.

Processing Costs per Ton Purchases Cost Tons

Newsprint Packaging Print Stock Per Ton Available

Newspaper $6.50 $11.00 ------ $15 600

Mixed Paper $9.75 $12,25 $9.50 $16 500

White Office Paper $4.75 $7.75 $8.50 $19 300

Cardboard $7.50 $8.50 ------ $17 400

The recycler wants to determine the least costly way of producing 500 tons of newsprint pulp, 600 tons of packaging paper pulp, and 300 tons of print stock quality pulp.

a. Create a spreadsheet model for this problem and solve it.

b. What is the optimal solution?