MT 2354 General Form of an LP Model where the cs, as and bs are constants determined from the problem and the xs are the decision variables
MT 2355 Components of Linear Programming An objective Decision variables Constraints Parameters
MT 2356 Assumptions of the LP Model Divisibility - basic units of xs are divisible Proportionality - as and cs are strictly proportional to the xs Additivity - each term in the objective function and constraints contains only one variable Deterministic - all cs, as and bs are known and measured without error Non-Negativity (caveat)
MT 2357 Sherwood Furniture Company Recently, Sherwood Furniture Company has been interested in developing a new line of stereo speaker cabinets. In the coming month, Sherwood expects to have excess capacity in its Assembly and Finishing departments and would like to experiment with two new models. One model is the Standard, a large, high-quality cabinet in a traditional design that can be sold in virtually unlimited quantities to several manufacturers of audio equipment. The other model is the Custom, a small, inexpensive cabinet in a novel design that a single buyer will purchase on an exclusive basis. Under the tentative terms of this agreement, the buyer will purchase as many Customs as Sherwood produces, up to 32 units. The Standard requires 4 hours in the Assembly Department and 8 hours in the Finishing Department, and each unit contributes $20 to profit. The Custom requires 3 hours in Assembly and 2 hours in Finishing, and each unit contributes $10 to profit. Current plans call for 120 hours to be available next month in Assembly and 160 hours in Finishing for cabinet production, and Sherwood desires to allocate this capacity in the most economical way.
MT 2358 Sherwood Furniture Company – Linear Equations
MT 2359 Sherwood Furniture Company – Graph Solution
MT 23529 Sherwood Furniture Company – Slack Calculation Point 3 Point 3
MT 23530 Sherwood Furniture Company – Slack Calculation Points 1, 2 & 3 Point 1Point 2Point 3
MT 23531 Sherwood Furniture Company – Slack Variables For each constraint the difference between the RHS and LHS (RHS-LHS). It is the amount of resource left over. Constraint 1; S 1 = 0 hrs. Constraint 2; S 2 = 0 hrs. Constraint 3; S 3 = 12 Custom
MT 23538 Pet Food Company A pet food company wants to find the optimal mix of ingredients, which will minimize the cost of a batch of food, subject to constraints on nutritional content. There are two ingredients, P1 and P2. P1 costs $5/lb. and P2 costs $8/lb. A batch of food must contain no more than 400 lbs. of P1 and must contain at least 200 lbs. of P2. A batch must contain a total of at least 500 lbs. What is the optimal (minimal cost) mix for a single batch of food?
MT 23554 Pet Food Co. – Slack Variables For each constraint the difference between the RHS and LHS (RHS-LHS). It is the amount of resource left over. Constraint 1; S 1 = 100 lbs.
MT 23555 Pet Food Co. – Surplus Variables For each constraint the difference between the LHS and RHS (LHS-RHS). It is the amount bt which a minimum requirement is exceeded. Constraint 2; S 2 = 0 lbs. Constraint 3; S 3 = 0 lbs.