Load the Solver Add-in
Excel includes a tool called Solver that uses techniques from operations research, a field focused on optimizing decisions, to solve all kinds of problems.
To load the Solver add-in, execute the following steps.
1. On the File tab, click Options.
2. Under Add-ins, select Solver Add-in and click on the Go button.
3. Check Solver Add-in and click OK.
4. You can find the Solver on the Data tab, in the Analyze group.
Formulate the Model
The model we are going to solve looks as follows in Excel.
1. To formulate this linear programming model, answer the following three questions.
a. What are the decisions to be made? For this problem, we need Excel to find out how much to order of each product (bicycles, mopeds and child seats).
b. What are the constraints on these decisions? The constraints here are that the amount of capital and storage used by the products cannot exceed the limited amount of capital and storage (resources) available. For example, each bicycle uses 300 units of capital and 0.5 unit of storage.
c. What is the overall measure of performance for these decisions? The overall measure of performance is the total profit of the three products, so the objective is to maximize this quantity.
2. To make the model easier to understand, create the following named ranges.
| Range Name | Cells |
|---|---|
| UnitProfit | C4:E4 |
| OrderSize | C12:E12 |
| ResourcesUsed | G7:G8 |
| ResourcesAvailable | I7:I8 |
| TotalProfit | I12 |
3. Insert the following three SUMPRODUCT functions.
Explanation: the amount of capital used equals the sumproduct of the range C7:E7 and OrderSize. The amount of storage used equals the sumproduct of the range C8:E8 and OrderSize. Total Profit equals the sumproduct of UnitProfit and OrderSize.
