Define and solve a problem by using Solver

In the following example, the level of advertising in each quarter affects the number of units sold, indirectly determining the amount of sales revenue, the associated expenses, and the profit. Solver can change the quarterly budgets for advertising (decision variable cells B5:C5), up to a total budget constraint of $20,000 (cell D5), until the total profit (objective cell D7) reaches the maximum possible amount. The values in the variable cells are used to calculate the profit for each quarter, so they are related to the formula objective cell D7, =SUM(Q1 Profit:Q2 Profit).

Variable cells

Constrained cell

 Objective cell

After Solver runs, the new values are as follows.

1. Click Data > Solver.

   

2. In Set Objective, enter a cell reference or name for the objective cell.

   : The objective cell must contain a formula.

3. Do one of the following:

   To	Do this
   Make the value of the objective cell as large as possible	Click Max.
   Make the value of the objective cell as small as possible	Click Min.
   Set the objective cell to a certain value	Click Value Of, and then type the value in the box.

4. In the By Changing Variable Cells box, enter a name or reference for each decision variable cell range. Separate the nonadjacent references with commas.

   The variable cells must be related directly or indirectly to the objective cell. You can specify up to 200 variable cells.

5. In the Subject to the Constraints box, add any constraints that you want to apply.

   To add a constraint, follow these steps:

   1. In the Solver Parameters dialog box, click Add.

   2. In the Cell Reference box, enter the cell reference or name of the cell range for which you want to constrain the value.

   3. On the <= relationship pop-up menu, select the relationship that you want between the referenced cell and the constraint.If you choose <=, =, or >=, in the Constraint box, type a number, a cell reference or name, or a formula.

      : You can only apply the int, bin, and dif relationships in constraints on decision variable cells.

   4. Do one of the following:

   To	Do this
   Accept the constraint and add another	Click Add.
   Accept the constraint and return to the Solver Parameters dialog box	Click OK.

6. Click Solve, and then do one of the following:

   To	Do this
   Keep the solution values on the sheet	Click Keep Solver Solution in the Solver Results dialog box.
   Restore the original data	Click Restore Original Values.

1. Click Data > Solver.

   

2. After you define a problem, in the Solver Parameters dialog box, click Options.

3. Select the Show Iteration Results check box to see the values of each trial solution, and then click OK.

4. In the Solver Parameters dialog box, click Solve.

5. In the Show Trial Solution dialog box, do one of the following:

   To	Do this
   Stop the solution process and display the Solver Results dialog box	Click Stop.
   Continue the solution process and display the next trial solution	Click Continue.

1. Click Data > Solver.

   

2. Click Options, and then in the Options or Solver Options dialog box, choose one or more of the following options:

   To	Do this
   Set solution time and iterations	On the All Methods tab, under Solving Limits, in the Max Time (Seconds) box, type the number of seconds that you want to allow for the solution time. Then, in the Iterations box, type the maximum number of iterations that you want to allow. : If the solution process reaches the maximum time or number of iterations before Solver finds a solution, Solver displays the Show Trial Solution dialog box.
   Set the degree of precision	On the All Methods tab, in the Constraint Precision box, type the degree of precision that you want. The smaller the number, the higher the precision.
   Set the degree of convergence	On the GRG Nonlinear or Evolutionary tab, in the Convergence box, type the amount of relative change that you want to allow in the last five iterations before Solver stops with a solution. The smaller the number, the less relative change is allowed.

3. Click OK.

4. In the Solver Parameters dialog box, click Solve or Close.

1. Click Data > Solver.

   

2. Click Load/Save, enter a cell range for the model area, and then click either Save or Load.

   When you save a model, enter the reference for the first cell of a vertical range of empty cells in which you want to place the problem model. When you load a model, enter the reference for the entire range of cells that contains the problem model.

   : You can save the last selections in the Solver Parameters dialog box with a sheet by saving the workbook. Each sheet in a workbook may have its own Solver selections, and all of them are saved. You can also define more than one problem for a sheet by clicking Load/Save to save problems individually.

1. Click Data > Solver.

   

2. On the Select a Solving Method pop-up menu, select one of the following: