Q.If the average fixed cost of producing 4 units of output is ₹60, then the value of total fixed cost for producing 5 units will be _____________. (Fill up the blank)
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Cost Concepts: From Everyday Intuition to Economic Precision
Think about the last time you bought something — say, a plate of chole bhature from a roadside stall. The stall owner paid for flour, oil, spices, gas, and the helper's wages. That's the obvious cost. But what about the rent of the cart? The interest on the loan he took to buy the stove? And what about the fact that he could have worked as a driver instead — the income he gave up? That last one is a cost too, though no money changed hands.
That's where economics begins to separate itself from simple accounting. Costs are not just what you pay; they are what you sacrifice.
The Core Idea: Opportunity Cost
The single most important cost concept in economics is opportunity cost. The NCERT Class-12 textbook defines it clearly: opportunity cost is the cost of the next best alternative foregone.
Opportunity cost = value of the next best alternative that you give up when you make a choice.
Why does this matter? Because resources — time, money, land, labour — are scarce. Every choice has a hidden cost: the thing you didn't choose. When the stall owner chooses to run his stall, he gives up the salary he could have earned as a driver. That foregone salary is a real cost, even if it never appears in his cash register.
Explicit vs Implicit Costs
From opportunity cost, we get two categories:
- Explicit costs — actual money payments made to others (wages, rent, raw materials, electricity bills). These are recorded in the books.
- Implicit costs — the value of self-owned resources used in production, for which no explicit payment is made. The owner's own labour, his own capital, his own land — these have opportunity costs that are not paid to anyone else.
In accounting, only explicit costs are counted. In economics, both explicit and implicit costs matter, because economics is about the full sacrifice.
Total, Average, and Marginal Costs
Once we move to production, costs are studied in relation to output. The NCERT textbook introduces these three measures:
Total Cost (TC)
The sum of all costs — explicit and implicit — incurred to produce a given level of output.
Average Cost (AC)
Cost per unit of output.
AC=QTC
where Q is the quantity of output.
Marginal Cost (MC)
The additional cost incurred to produce one more unit of output.
MC=ΔQΔTC
where Δ means "change in".
MC is the cost of the last unit produced. AC is the cost of all units averaged. They behave differently as output changes.
Short-Run vs Long-Run Costs
This distinction is crucial. In the short run, at least one factor of production is fixed (typically capital — factory size, machinery). In the long run, all factors are variable.
Short-Run Cost Categories
| Cost | Symbol | Definition |
|---|---|---|
| Total Fixed Cost | TFC | Cost that does not change with output (rent, insurance, interest on loans) |
| Total Variable Cost | TVC | Cost that changes with output (raw materials, wages of daily workers, electricity) |
| Total Cost | TC | TC=TFC+TVC |
From these, we derive:
- Average Fixed Cost (AFC) = QTFC — falls continuously as output rises.
- Average Variable Cost (AVC) = QTVC — typically U-shaped.
- Average Cost (AC) = QTC=AFC+AVC
A common mistake: thinking that AC and AVC are the same. They are not. AC includes AFC, so AC always lies above AVC. The gap between them is AFC, which shrinks as output increases.
The Shape of the Curves
Imagine a graph with output on the horizontal axis and cost on the vertical axis.
- TFC is a horizontal straight line — it never changes. …
Part (b)Concept understanding — Cost Concepts
Cost Concepts: From Everyday Intuition to Economic Precision
Think about the last time you bought something — say, a plate of chole bhature from a roadside stall. The stall owner paid for flour, oil, spices, gas, and the helper's wages. That's the obvious cost. But what about the rent of the cart? The interest on the loan he took to buy the stove? And what about the fact that he could have worked as a driver instead — the income he gave up? That last one is a cost too, though no money changed hands.
That's where economics begins to separate itself from simple accounting. Costs are not just what you pay; they are what you sacrifice.
The Core Idea: Opportunity Cost
The single most important cost concept in economics is opportunity cost. The NCERT Class-12 textbook defines it clearly: opportunity cost is the cost of the next best alternative foregone.
Opportunity cost = value of the next best alternative that you give up when you make a choice.
Why does this matter? Because resources — time, money, land, labour — are scarce. Every choice has a hidden cost: the thing you didn't choose. When the stall owner chooses to run his stall, he gives up the salary he could have earned as a driver. That foregone salary is a real cost, even if it never appears in his cash register.
Explicit vs Implicit Costs
From opportunity cost, we get two categories:
- Explicit costs — actual money payments made to others (wages, rent, raw materials, electricity bills). These are recorded in the books.
- Implicit costs — the value of self-owned resources used in production, for which no explicit payment is made. The owner's own labour, his own capital, his own land — these have opportunity costs that are not paid to anyone else.
In accounting, only explicit costs are counted. In economics, both explicit and implicit costs matter, because economics is about the full sacrifice.
Total, Average, and Marginal Costs
Once we move to production, costs are studied in relation to output. The NCERT textbook introduces these three measures:
Total Cost (TC)
The sum of all costs — explicit and implicit — incurred to produce a given level of output.
Average Cost (AC)
Cost per unit of output.
AC=QTC
where Q is the quantity of output.
Marginal Cost (MC)
The additional cost incurred to produce one more unit of output.
MC=ΔQΔTC
where Δ means "change in".
MC is the cost of the last unit produced. AC is the cost of all units averaged. They behave differently as output changes.
Short-Run vs Long-Run Costs
This distinction is crucial. In the short run, at least one factor of production is fixed (typically capital — factory size, machinery). In the long run, all factors are variable.
Short-Run Cost Categories
| Cost | Symbol | Definition |
|---|---|---|
| Total Fixed Cost | TFC | Cost that does not change with output (rent, insurance, interest on loans) |
| Total Variable Cost | TVC | Cost that changes with output (raw materials, wages of daily workers, electricity) |
| Total Cost | TC | TC=TFC+TVC |
From these, we derive:
- Average Fixed Cost (AFC) = QTFC — falls continuously as output rises.
- Average Variable Cost (AVC) = QTVC — typically U-shaped.
- Average Cost (AC) = QTC=AFC+AVC
A common mistake: thinking that AC and AVC are the same. They are not. AC includes AFC, so AC always lies above AVC. The gap between them is AFC, which shrinks as output increases.
The Shape of the Curves
Imagine a graph with output on the horizontal axis and cost on the vertical axis.
- TFC is a horizontal straight line — it never changes. …
Part (a)
Total Fixed Cost (TFC) does not change with output. Given AFC at 4 units is ₹60:
TFC=AFC×Q=60×4=₹240 …
Part (a): TFC is constant with output; TFC = AFC × Q = 60 × 4 = ₹240, so for 5 units it is still ₹240.
Part (b): Two examples of variable cost — cost of raw materials and wages of casual labour.
Part (a)
Average Fixed Cost (AFC) is total fixed cost spread over output: AFC=QTFC. The key property of Total Fixed Cost (TFC) is that it does not vary with the level of output in the short run — it is the same at 0, 4, or 5 units.
Recover TFC from the given data at Q=4:
TFC=AFC×Q=60×4=₹240
Because TFC is fixed, producing 5 units does not change it. …
- JAC Jharkhand Intermediate Class 12 (Commerce) 2025Set ANNUAL1 markMCQQ.Which of the following is not an example of a variable cost?(a) Cost of raw material(b) Rent for building(c) Per unit electricity bill(d) Commission
›Reveal solutionSolution
Rent for a building is a fixed cost, not variable.
Variable costs change with the level of output (cost of raw materials, per-unit electricity consumed, commission on sales). Rent for a building is a fixed cost — it must be paid at the same amount whether output is large …
- JAC Jharkhand Intermediate Class 12 (Commerce) 2024Set ANNUAL1 markMCQQ.Which of the following curves has a 'U' shape?(a) Average product(b) Marginal cost(c) Total cost(d) None of these
›Reveal solutionSolution
The marginal cost curve is U-shaped.
Because of the law of variable proportions, marginal cost first falls (increasing returns), reaches a minimum, and then rises (diminishing returns), giving the MC curve a U-shape. The average product curve is dome/inverted-U sha …
- JAC Jharkhand Intermediate Class 12 (Commerce) 2023Set ANNUAL1 markMCQQ.Fixed cost of production of an article is Rs. 60. What will be the average fixed cost of producing 10 units of that article?(a) Rs. 50(b) Rs. 25(c) Rs. 6(d) Rs. 60
›Reveal solutionSolution
AFC = TFC/Q = 60/10 = Rs. 6.
Average Fixed Cost (AFC) is total fixed cost spread over the units produced: AFC = TFC ÷ output. Here TFC = Rs. 60 and output = 10 …
- JAC Jharkhand Intermediate Class 12 (Commerce) 2023Set ANNUAL1 markMCQQ.Which of the following is correct?(a) TVC = TC - TFC(b) TC = TFC - TVC(c) TFC = TVC + TC(d) TC = TVC x TFC
›Reveal solutionSolution
The correct relation is TVC = TC − TFC.
Total cost is the sum of total fixed cost and total variable cost: TC = TFC + TVC. Rearranging, TVC = TC − TFC. The other options reverse or misstate thi …
- JAC Jharkhand Intermediate Class 12 (Commerce) 2023Set ANNUAL1 markMCQQ.Which cost does not change with the change in output?(a) Marginal cost(b) Total fixed cost(c) Average fixed cost(d) Average variable cost
›Reveal solutionSolution
Total fixed cost stays constant as output changes.
Fixed costs (rent, salaries of permanent staff, insurance) are incurred on fixed factors and do not vary with output; total fixed cost (TFC) therefore remains constant at all levels of output. Marginal cost, …
- JAC Jharkhand Intermediate Class 12 (Commerce) 2023Set ANNUAL1 markMCQQ.The shape of average cost curve is(a) U-shaped(b) Line parallel to x-axis(c) L-shaped(d) None of these
›Reveal solutionSolution
The average (total) cost curve is U-shaped.
In the short run average cost first falls (as fixed cost is spread over more units and efficiency rises), reaches a minimum, and then rises (as the law of variable proportions causes costs to incr …
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