Help with Linear Programming

Hello,

I am seeking help with an excel assignment that I have.
Here is the problem:

"A firm produces four products: A, B, C, and D. Each unit of product A requires two hours of milling, one hour of assembly, and $10 worth of in-process inventory. Each unit of B requires one hour of milling, one hour of assembly, and $5 worth of in-process inventory. Each unit of C requires 2.5 hours of milling, 2.5 hours of assembly, and $2 worth of in-process inventory. Finally, each unit of product D requires five hours of milling, no assembly, and $12 of in-process inventory.


The firm has 120 thousand hours of milling time and 160 thousand hours of assembly time available. In addition, not more than $1 million may be tied up in in-process inventory.


Each unit of product A returns a profit of $40; each unit of B returns a profit of $24; each unit of product C returns a profit of $36; and each unit of product D returns a profit of $23. Not more than 20,000 units of product A can be sold; not more than 16,000 units of product C can be sold; and any number of units of products B and D may be sold. However, at least 10,000 units of D must be produced and sold to satisfy a contract agreement."

I think I almost have the solution, but there must be something that I am overlooking because I am getting weird numbers after using the solver. I am pretty sure that the problem lies in how I set up the # of units sold, but I am not sure how to fix it.
Any help would be greatly appreciated.

Cross listed: http://chandoo.org/forum/threads/hel...g-excel.18846/

Normaly forum members should not solve home work problems but as "sell-by date" for this problem must have passed I'll upload a modified solution to the OP's original setup.

Alf