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How to Calculate Shadow Price

Shadow Price Formula:

\[ \text{Shadow Price} = \frac{\text{Change in Objective}}{\text{Change in Constraint}} \]

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1. What is Shadow Price?

Shadow Price represents the rate of change in the objective function value per unit increase in a constraint's right-hand side in linear programming. It indicates the marginal value of relaxing a constraint and is a key concept in sensitivity analysis.

2. How Does the Calculator Work?

The calculator uses the Shadow Price formula:

\[ \text{Shadow Price} = \frac{\text{Change in Objective}}{\text{Change in Constraint}} \]

Where:

Explanation: The shadow price measures how much the optimal value of the objective function would improve if the constraint was relaxed by one unit.

3. Importance of Shadow Price Calculation

Details: Shadow prices are crucial for understanding the sensitivity of optimal solutions to changes in constraints, helping decision-makers identify which constraints are binding and where resources should be allocated for maximum benefit.

4. Using the Calculator

Tips: Enter the change in objective value (in currency units) and the corresponding change in constraint (in units). The change in constraint must be non-zero for valid calculation.

5. Frequently Asked Questions (FAQ)

Q1: What does a zero shadow price indicate?
A: A zero shadow price indicates that the constraint is not binding at the optimal solution, meaning relaxing the constraint won't improve the objective function.

Q2: Can shadow prices be negative?
A: Yes, shadow prices can be negative, indicating that increasing the constraint's right-hand side would actually worsen the objective function value.

Q3: How are shadow prices used in resource allocation?
A: Shadow prices help identify which resources are most valuable at the margin, guiding decisions about where to invest additional resources for maximum return.

Q4: Do shadow prices remain constant?
A: Shadow prices are valid only within the allowable range of constraint changes. Beyond certain limits, the basis of the optimal solution may change.

Q5: How do shadow prices relate to dual variables?
A: In linear programming, shadow prices are equivalent to the optimal values of the dual variables associated with the constraints.

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