Production and Costs
Class 12 · Economics
4 ideas in Class 12 Economics, explained in plain words, with games and quizzes to practise.
Production Function, Factors and Isoquants
Part of: Recipes of Production
The production function gives maximum output from inputs at fixed technology; better know-how makes a new one. In the short run one factor is fixed and only the other moves; in the long run all move. An isoquant joins mixes giving equal output: 18 units arise from 2 labour with 3 capital or 3 labour with 2 capital. With positive marginal products, isoquants slope down.
Why it matters. Every hiring and machine decision is a move along or between isoquants. Learners who sort fixed from variable inputs can tell which costs can change today and which only later.
Formulas
- q = f(L, K)
- Isoquant q = 18: (2L, 3K) and (3L, 2K)
- Fixed factor stays; variable factor moves in the short run
Key words
- Production function
- : Maximum output from given inputs with given technology.
- Factors of production
- : Inputs used in making output, like labour and capital.
- Fixed factor
- : Input stuck for now, like land this season.
- Variable factor
- : Input changeable now, like daily labour.
- Short run
- : Only the changeable input varies.
- Long run
- : All inputs can change.
- Isoquant
- : Input mixes yielding the same output.
- Factor proportions
- : Ratio in which inputs combine.
Try it in two minutes
- Ask the child what a farmer cannot change this season.
- Ask what the farmer can change tomorrow.
- Explain that equal-output mixes form an isoquant.
Try at home. Pick a home chore and sort its inputs into fixed and variable.
Total, Average and Marginal Product
Part of: More Hands, Then Crowding
With fixed land, total product runs 0, 8, 20, 30, 36, 38 as labour rises 0 to 5. Marginal products are 8, 12, 10, 6, 2: rising to the second worker, then falling as land crowds. Averages run 8, 10, 10, 9, 7.6. MP crosses AP at 10 when labour is 3; while MP stays above AP, AP rises, and after, it falls.
Why it matters. Every staffing choice faces this hump. Learners who can compute MP and AP know when the next hire still pays and when crowding eats the gain.
Formulas
- AP = TP / L
- MP of nth unit = TP at n - TP at n-1
- TP = sum of all MPs so far
- Worked TP: 0, 8, 20, 30, 36, 38; MP: 8, 12, 10, 6, 2
Key words
- Total product
- : Output from the variable input with others fixed.
- Average product
- : Output per unit of the variable input.
- Marginal product
- : Extra output from one more unit of input.
- Law of variable proportions
- : MP first rising then falling.
- Increasing phase
- : MP rising as proportions improve.
- Diminishing phase
- : MP falling as crowding sets in.
- Average of marginals
- : AP is the mean of all MPs so far.
- Crowding
- : Land getting crowded with workers.
Try it in two minutes
- Ask the child why the second helper adds more than the first.
- Ask why the sixth helper adds almost nothing.
- Explain that crowding turns the extra down.
Try at home. Invent a TP schedule and find where MP turns down.
Returns to Scale and Short Run Costs
Part of: Costs and Their Curves
Doubling all inputs doubles output under CRS, more than doubles under IRS and less than doubles under DRS. With TFC 30 and TVC 0, 12, 22, 30, 40, 55, total cost runs 30, 42, 52, 60, 70, 85. SAC runs 42, 26, 20, 17.5, 17; AVC runs 12, 11, 10, 10, 11; AFC runs 30, 15, 10, 7.5, 6; SMC runs 12, 10, 8, 10, 15. Fixed cost never changes output decisions at the margin.
Why it matters. Every quote a firm gives rests on these splits. Learners who can build the table see which costs matter for the next unit and which are already sunk.
Formulas
- TC = TVC + TFC
- SAC = TC / q; AVC = TVC / q; AFC = TFC / q
- SAC = AVC + AFC
- SMC of nth unit = TC at n - TC at n-1
- Worked TC: 30, 42, 52, 60, 70, 85; SMC: 12, 10, 8, 10, 15
Key words
- Constant returns to scale
- : Doubling inputs doubles output.
- Increasing returns to scale
- : Doubling inputs more than doubles output.
- Decreasing returns to scale
- : Doubling inputs less than doubles output.
- Total fixed cost
- : Cost of fixed inputs, same at all outputs.
- Total variable cost
- : Cost of variable inputs, rising with output.
- Total cost
- : Fixed plus variable cost.
- Average cost
- : Cost per unit of output.
- Marginal cost
- : Extra cost of one more unit.
Try it in two minutes
- Ask the child which home costs stay even with zero use.
- Ask which costs grow with more use.
- Explain that per-unit cost is the total shared out.
Try at home. Build a cost table with TFC 30 and check that SAC equals AVC plus AFC.
Shapes of Cost Curves and the Long Run
Part of: Costs and Their Curves
SMC first falls then rises in a U, and AVC follows the same valley; SMC cuts AVC from below at its minimum, here 10 at 3 and 4 units. SAC adds ever-falling AFC, so its minimum at 17 sits right of AVC's. AFC times quantity always equals 30, a rectangular hyperbola. In the long run with no fixed costs, LRAC falls under IRS, flattens under CRS and rises under DRS, making its own U with LRMC cutting it at the dip.
Why it matters. Every shutdown and expansion choice reads these valleys. Learners who can find the crossings know the cheapest output today and why bigness first helps, then hurts.
Formulas
- SMC cuts AVC and SAC from below at their minimum
- AFC x q = TFC always
- TVC at q = area under SMC up to q
- LRAC falls with IRS, flat with CRS, rises with DRS
Key words
- SMC curve
- : U-shaped extra cost curve.
- AVC curve
- : U-shaped variable cost per unit.
- SAC curve
- : U-shaped total cost per unit.
- AFC curve
- : Ever-falling fixed cost per unit.
- Long run average cost
- : Cost per unit with all inputs variable.
- Long run marginal cost
- : Extra cost with all inputs variable.
- Economies of scale
- : Falling LRAC from IRS.
- Diseconomies of scale
- : Rising LRAC from DRS.
Try it in two minutes
- Ask the child why per-unit cost first falls.
- Ask what pulls it back up later.
- Explain that the extra line crosses each average at its dip.
Try at home. Plot the worked SAC and SMC and mark both crossing points.
What your child will practise
- Production Function, Factors and Isoquants: Candy Quick Fire (Quick Fire)
- Production Function, Factors and Isoquants: Space Puzzle (Clue Puzzle)
- Returns to Scale and Short Run Costs: Ocean Puzzle (Clue Puzzle)
- Shapes of Cost Curves and the Long Run: Candy Quest (Flip and Match)
- Total, Average and Marginal Product: Ocean Quick Fire (Quick Fire)
- Quiz: Production Function, Factors and Isoquants (8 questions)
- Quiz: Returns to Scale and Short Run Costs (8 questions)
- Quiz: Shapes of Cost Curves and the Long Run (8 questions)
- Quiz: Total, Average and Marginal Product (8 questions)