Solver for optimization in Excel - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the objective cell in Solver.

Excel

SolverOk SetCell:=Range("[1]"), MaxMinVal:=1

Drag options to blanks, or click blank then click option'

AD1

BC1

CB1

DA1

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing a cell that does not contain the objective formula.

Using a cell outside the data range.

The objective cell is usually the cell where the result to optimize is calculated. Here, "A1" is the correct cell reference.

2fill in blank

medium

Complete the code to add a constraint in Solver.

Excel

SolverAdd CellRef:=Range("B2"), Relation:=2, FormulaText:=Range("[1]")

Drag options to blanks, or click blank then click option'

AC2

BA2

CD2

DE2

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong cell reference for the constraint value.

Confusing the cell to constrain with the constraint limit.

The constraint compares cell B2 to cell C2. So the formula text should be "C2".

3fill in blank

hard

Fix the error in the Solver code to solve the model.

Excel

SolverSolve UserFinish:= [1]

Drag options to blanks, or click blank then click option'

A0

B1

CTrue

DFalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using False instead of True causes Solver to skip showing results.

Using numeric values instead of Boolean.

Setting UserFinish to True displays the Solver Results dialog after solving. False suppresses the results dialog.

4fill in blank

hard

Fill both blanks to set Solver to minimize the objective and use the GRG Nonlinear solving method.

Excel

SolverOk SetCell:=Range("A1"), MaxMinVal:=[1], Engine:=[2]

Drag options to blanks, or click blank then click option'

A1

B2

C3

D4

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 for MaxMinVal to minimize instead of maximize.

Choosing the wrong engine number for the solving method.

MaxMinVal=2 means minimize the objective. Engine=2 selects the GRG Nonlinear solving method.

5fill in blank

hard

Fill all three blanks to add a constraint that cell B3 must be less than or equal to 100.

Excel

SolverAdd CellRef:=Range("[1]"), Relation:=[2], FormulaText:=[3]

Drag options to blanks, or click blank then click option'

AB3

B1

C100

D2

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong relation number for less than or equal to.

Putting the cell reference or formula text in the wrong place.

CellRef is "B3". Relation 2 means less than or equal to. FormulaText is 100, the limit.

Practice

1. What is the main purpose of Excel's Solver tool?

easy

A. To format cells with colors

B. To create charts and graphs automatically

C. To sort data alphabetically

D. To find the best values for variables to achieve a goal

Solution

1. Step 1: Understand Solver's function

   Solver is designed to adjust variables to optimize a target value.

2. Step 2: Compare options

   Only To find the best values for variables to achieve a goal describes finding best values to reach a goal, which matches Solver's purpose.

3. Final Answer:

   To find the best values for variables to achieve a goal -> Option D

4. Quick Check:

   Solver = optimization tool [OK]

Hint: Solver finds best numbers to reach your goal [OK]

Common Mistakes:

• Confusing Solver with chart tools
• Thinking Solver sorts or formats data
• Assuming Solver only works with text

2. Which of these is the correct way to set the objective cell in Solver?

easy

A. Select any empty cell

B. Select the cell with the formula you want to optimize

C. Select the entire worksheet

D. Select only cells with text

Solution

1. Step 1: Identify the objective cell role

   The objective cell contains the formula Solver tries to maximize, minimize, or set to a value.

2. Step 2: Evaluate options

   Only Select the cell with the formula you want to optimize correctly states selecting the formula cell to optimize.

3. Final Answer:

   Select the cell with the formula you want to optimize -> Option B

4. Quick Check:

   Objective cell = formula cell [OK]

Hint: Objective cell must have the formula to optimize [OK]

Common Mistakes:

• Choosing empty cells without formulas
• Selecting too many cells
• Picking cells with only text

3. Given this setup: Objective cell B5 = SUM(B1:B4), variable cells B1:B4, and constraint B1>=0, what will Solver do if you set objective to maximize B5?

medium

A. Return an error because constraints are invalid

B. Decrease values in B1:B4 to minimize the sum

C. Increase values in B1:B4 to maximize the sum

D. Ignore constraints and set B1:B4 to zero

Solution

1. Step 1: Understand objective and variables

   The objective is to maximize the sum in B5, which depends on B1:B4 values.

2. Step 2: Apply constraints

   Constraint B1>=0 means B1 cannot be negative, but no upper limit is set.

3. Step 3: Predict Solver behavior

   Solver will increase B1:B4 values (within constraints) to maximize the sum.

4. Final Answer:

   Increase values in B1:B4 to maximize the sum -> Option C

5. Quick Check:

   Maximize sum = increase variables [OK]

Hint: Maximize sum by increasing variable cells [OK]

Common Mistakes:

• Thinking Solver minimizes when set to maximize
• Ignoring constraints
• Assuming Solver returns errors without reason

4. You set Solver to minimize cell C10 by changing C1:C5 but get an error saying 'No feasible solution found'. What is a likely cause?

medium

A. Constraints are too strict or conflicting

B. Objective cell has no formula

C. Variable cells contain text instead of numbers

D. Solver add-in is not installed

Solution

1. Step 1: Understand 'No feasible solution' error

   This error means Solver cannot find values meeting all constraints.

2. Step 2: Analyze possible causes

   Too strict or conflicting constraints often cause no solution.

3. Step 3: Evaluate other options

   Objective cell without formula or text in variables cause different errors; Solver add-in missing prevents running Solver.

4. Final Answer:

   Constraints are too strict or conflicting -> Option A

5. Quick Check:

   No feasible solution = conflicting constraints [OK]

Hint: Check constraints if Solver finds no solution [OK]

Common Mistakes:

• Ignoring constraint conflicts
• Assuming Solver add-in missing causes this error
• Not verifying variable cell data types

5. You want to minimize total cost in cell D10 by changing quantities in D1:D5. Each quantity must be an integer between 1 and 10. How do you set up Solver correctly?

hard

A. Set objective to minimize D10, variable cells D1:D5, add constraints D1:D5 >=1, D1:D5 <=10, and select 'Make Integer' for D1:D5

B. Set objective to maximize D10, variable cells D1:D5, no constraints needed

C. Set objective to minimize D10, variable cells D1:D5, add constraint D1:D5 = 5 only

D. Set objective to minimize D10, variable cells D1:D5, add constraint D1:D5 text only

Solution

1. Step 1: Define objective and variables

   Objective is to minimize D10 by changing D1:D5 quantities.

2. Step 2: Add constraints for integer and range

   Quantities must be integers between 1 and 10, so add constraints D1:D5 >=1, D1:D5 <=10, and set 'Make Integer' for D1:D5.

3. Step 3: Evaluate options

   Only Set objective to minimize D10, variable cells D1:D5, add constraints D1:D5 >=1, D1:D5 <=10, and select 'Make Integer' for D1:D5 correctly sets objective, variables, and all constraints including integer requirement.

4. Final Answer:

   Set objective to minimize D10, variable cells D1:D5, add constraints D1:D5 >=1, D1:D5 <=10, and select 'Make Integer' for D1:D5 -> Option A

5. Quick Check:

   Integer constraints + bounds = correct setup [OK]

Hint: Add integer and range constraints for quantities [OK]

Common Mistakes:

• Forgetting to set integer constraint
• Using maximize instead of minimize
• Setting wrong or missing constraints