Cost structure relationships in a chemical process plant: which of the following expressions is NOT correct?

Introduction / Context:
Accurate cost definitions are the backbone of pricing, profitability analysis, and budgeting in process industries. Mixing up manufacturing cost, general expenses, and total product cost leads to errors in break-even and ROI calculations.

Given Data / Assumptions:

• Standard chemical engineering cost definitions apply.
• Total product cost includes both manufacturing cost and general expenses.

Concept / Approach:
Manufacturing cost typically comprises direct production cost (raw materials, direct labor, operating supplies), fixed charges (depreciation, insurance, taxes), and plant overhead. General expenses cover administrative, selling, distribution, and R&D. Total product cost is manufacturing cost plus general expenses.

Step-by-Step Solution:
1) Check (a): Matches standard definition of manufacturing cost.2) Check (b): General expenses are admin plus selling/distribution; correct.3) Check (c): Total product cost = manufacturing cost + general expenses; correct.4) Check (d): Omits general expenses; hence, it is not correct.

Verification / Alternative check:
Referencing common plant design texts confirms the decomposition of costs into direct, fixed, overhead, and general expense categories culminating in total product cost.

Why Other Options Are Wrong:
They are standard expressions accepted in plant cost accounting; only (d) leaves out general expenses, so it is incorrect.

Common Pitfalls:
Confusing manufacturing cost with total product cost; forgetting selling and administration in pricing decisions.

Final Answer:
Total product cost = direct production cost + plant overhead cost