Students step onto the factory floor to analyze a massive surge in total material costs. Using a three-factor chain substitution model (production volume, material efficiency, and raw material price), they must investigate a real-world scenario. They will act as mathematical detectives to prove whether the production manager is truly guilty of wastefulness, or if the cost spike was driven entirely by an external macroeconomic shock. 

Roadmap to Solution:

Step 1: Establish the strict analytical sequence for costs: Production Volume (Q) → Material Efficiency (Z) → Market Price (C).

Step 2: Isolate the change in Material Efficiency (Z₁ - Z₀). Hint: If we used less material per unit, this number must be negative!

Step 3: Apply the cascade rule for the factor preceding efficiency. Since Volume (Q) comes first in the chain, use its new, actual value (Q₁).

Step 4: Apply the cascade rule for the factor succeeding efficiency. Since Price (C) comes last, keep it frozen at its baseline value (C₀).

Step 5 (Efficiency Impact): Multiply these three components together: Q₁ × (Z₁ - Z₀) × C₀.