chapter 3 -- modeling and solving lp problems rev

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Modeling and Solving LP Problems 3.4 | A Spreadsheet Model for the Blue Ridge Hot Tubs Problem

Figure 3.1

EXCEL Note: =SUMPRODUCT(B5:C5,B6:C6) is equivalent to B5*B6 + C5*C6 (or, a sum of products)

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EXCEL: Data | Solver If not activated then: Office Button | EXCEL Options

Add-Ins | Select from list | Go

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Target cell: ________ (which cell is our objective?) Equal to: ________ (do we want max or min?) Changing cells: ________ (which cells are our decision variable cells?) Each constraint has three parts:

Fill in these blanks: Constraint Cell Reference Relationship Constraint Pumps Labor Tubing The first one looks like in EXCEL:

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So far it looks like this:

Go to Options and Select

• Assume Linear • Assume Non-Negativity

Back to Solver Parameters Dialog Box and select SOLVE This is what you hope to see:

Click OK

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Now you see the solution:

What does this tell you? Decision? Objective? Constraints? Solver Sensitivity Report

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Your Turn: Problem 3-12 In words, what are the: Decision variables? Objective function? Constraints? Algebraically, what are the: Decision variables? Objective function? Constraints? Identify “zones” (dec var, obj function, constraints) on the spreadsheet for setting up this problem: (hint: look at the Hot Tubs spreadsheet)

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3.8 | Make vs. Buy Decisions

In words, what are the: Decision variables? Objective function? Constraints? Algebraically, what are the: Decision variables? Objective function? Constraints?

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Fig 3.17

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Problem 3-181 In words, what are the: Decision variables? Objective function? Constraints? Algebraically, what are the: Decision variables? Objective function? Constraints?

1 Solution at end of notes

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3.9 | An Investment Problem

In words, what are the: Decision variables? Objective function? Constraints? Algebraically, what are the: Decision variables? Objective function? Constraints?

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Fig 3.20

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3.12 | A Production and Inventory Planning Problem

Fig 3.31

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3.10 | A Transportation Problem Distance (in miles) Between Groves and Plants Grove Ocala Orlando Leesburg Mt. Dora 21 50 40 Eustis 35 30 22 Clermont 55 20 25 Fig 3.23

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Fig 3.24

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Your Turn: Problem 3-292

2 Solution at end of notes

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Comprehensive Examples Case 3-3 Identify the problem: Why would LP help us? What are we trying to decide? What is the goal? Any limiting factors?

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Case 3-4 Identify the problem: Why would LP help us? What are we trying to decide? What is the goal? Any limiting factors?

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Your Turn Partial Solutions Problem 3-18

Problem 3-29