Theory of Production

Contents

What is Production?
Factors of Production
Production Function
Short Run vs. Long Run
Fixed Factor vs. Variable Factor
Total Product (TP)
Average Product (AP)
Marginal Product (MP)
TP, AP, MP — Numerical Table
Law of Variable Proportions
Three Phases of LVP
TP & MP Diagram
Relationship: TP & MP
Law of Diminishing Returns
Relationship: AP & MP
AP & MP Diagram
Most Important Exam Points
Likely Exam Questions
Quick Revision Sheet

Section 01

What is Production?

Definition Production is a key economic activity that converts resources (inputs) into goods and services (outputs). It is the creation and addition of utility — not the creation of matter.

Production refers to the process by which raw materials and inputs are transformed into finished goods and services that satisfy human wants. The primary objective of production is the satisfaction of human wants through the creation of utility.

Critical Distinction — What Production Is NOT

Important Conceptual Point Production is NOT the creation of matter. You cannot create matter (raw resources). What you CAN do is add utility to existing matter.

Example: You cannot create water, but you can use water to generate electricity. The water (matter) exists — you added utility to it by converting it into electrical energy.

Why is Production Important?

Measures Economic Performance: GDP (Gross Domestic Product) is entirely production-based. More production = stronger economy.
Determines Standard of Living: Higher production → more employment → more income → richer economy. Developed nations (e.g., China) have superior production capacity.
Firm Survival: Firms survive by producing at minimum cost and maximising profit. Efficient production is the core business objective.

Section 02

Factors of Production Exam Favourite

Definition Factors of Production are the inputs or resources required to produce goods and services. There are four main factors: Land, Labour, Capital, and Entrepreneurship.

Factor	Definition	Key Feature	Examples
Land	All natural resources used in production	Free gift of nature — cannot be created or destroyed	Soil, water, minerals, forests, climate
Labour	Human effort (physical or mental) used in production	Must be productive; effort must generate output	Workers, professionals, service providers, teachers
Capital	Man-made resources used to produce other goods	Created by humans; required for all production	Machinery, tools, factories, money, buildings
Entrepreneurship	The act of organising land, labour and capital to produce	Takes risk; combines all other factors; seeks profit	Business owners, founders, investors

Key Points — Entrepreneurship Two most important characteristics of an Entrepreneur: (1) Innovation — introduces new ideas, methods, or products. (2) Profit — the primary motivation and reward for taking risk.

Key Points — Land Land is a free gift of nature. It includes not just physical land/soil but ALL natural resources: water bodies, mineral deposits, forests, sunlight, climate conditions. Its supply is fixed and cannot be increased or decreased.

Key Points — Labour Labour includes both physical labour (farming, construction) and mental labour (teaching, management). The labour must be productive — it must contribute to output. Unproductive time (e.g., idle scrolling) is not considered labour in economics.

Section 03

Production Function Important

Definition The Production Function shows the relationship between the quantity of inputs used and the maximum quantity of output that can be produced. It is a technological relationship.

General Form Q = f(A, B, C, ... N)

where: Q = Quantity of Output (Dependent Variable)
f = Functional relationship
A, B, C ... N = Inputs (Land, Labour, Capital, Enterprise) — Independent Variables

Simplified Form: Q = f(L, K)
where L = Labour, K = Capital

Key Assumptions of the Production Function

Specific Time Period: The production function is defined for a particular time frame — not across long, indefinite periods.
Constant Technology: Technology is held constant. No technological progress is assumed during the period under study.
Maximum Efficiency: It is assumed that inputs are used at their best capacity utilisation — the maximum possible output is obtained from given inputs.

Section 04

Short Run vs. Long Run Core Concept

Critical Distinction — Not About Calendar Time In Economics, Short Run and Long Run are NOT defined by a fixed calendar period (unlike Accounting where <1 year = short term, etc.). They are defined by whether factors of production can be changed or not.

Concept	Definition	Factor Status	Law Applicable
Short Run	A time period in which at least one factor of production is fixed and cannot be changed	Some factors Fixed + Some Variable (At least ONE is fixed)	Law of Variable Proportions
Long Run	A time period in which ALL factors of production can be varied	ALL factors are Variable (None is fixed)	Returns to Scale (not in syllabus)

Quick Test — Short Run or Long Run?

Rule If even ONE factor cannot be changed → it is the Short Run.
Only when ALL factors can be changed → it is the Long Run.

Even if a firm can change all factors within one week — that one week is still the Long Run (because all factors changed). Time does not determine the run — changeability of factors does.

Section 05

Fixed Factor vs. Variable Factor

Basis	Fixed Factor	Variable Factor
Definition	Factors that CANNOT be changed in the short run	Factors that CAN be changed in the short run
Applicability	Short Run only	Both Short Run and Long Run
Typical Example	Capital (Machinery, Plant, Factory)	Labour, Raw Materials
Output Effect	Output cannot increase by changing this	Output changes when this factor changes

Why Capital is Usually the Fixed Factor Capital (machinery, plant capacity) cannot be instantly arranged. You cannot install a new factory in 15 days. Labour and raw materials can be arranged more quickly. Hence in short-run analysis, Capital (K) is typically treated as the Fixed Factor and Labour (L) as the Variable Factor.

Section 06

Total Product (TP)

Definition Total Product (TP) is the total quantity of output produced by a firm using a given quantity of variable factor, keeping the fixed factor constant. It is the total output at any given level of variable input.

Formula TP = Sum of Marginal Products → TP = Σ MP

Also: TP (at n units) = TP(n-1) + MP(n)

Section 07

Average Product (AP)

Definition Average Product (AP) is the output produced per unit of variable factor employed. It tells us how much output, on average, each unit of the variable factor is producing.

Formula AP = TP / Q

where Q = Quantity of Variable Factor (e.g., number of labourers)

Section 08

Marginal Product (MP) Most Important

Definition Marginal Product (MP) is the additional output produced when one more unit of the variable factor is employed, keeping all other factors constant. It is the change in Total Product due to one unit change in the variable factor.

Formulae MP = ΔTP / ΔQ → Change in Total Product / Change in Quantity of Variable Factor

MP(n) = TP(n) − TP(n−1) → Subtract previous TP from current TP

Note: The second formula (subtraction) does not always work accurately. Prefer ΔTP/ΔQ.

Section 09

TP, AP, MP — Numerical Illustration Exam Favourite

The table below illustrates how TP, AP and MP change as we increase the variable factor (Labour) while keeping the fixed factor (Machine/Capital) constant.

Labour (L) — Variable Factor	TP (Total Product)	AP = TP/L	MP = ΔTP/ΔL	Phase
0	0	—	—	—
1	10	10.0	10	Phase I TP rises at Increasing Rate MP rising
2	30	15.0	20 ↑ (Max MP)	Phase I TP rises at Increasing Rate MP rising
3	45	15.0	15 ↓	Phase II TP rises at Diminishing Rate MP falling
4	45	11.3	0 (TP Max)	Phase II TP rises at Diminishing Rate MP falling
5	30	6.0	−15 (negative)	Phase III TP falling MP negative
6	24	4.0	−6 (negative)	Phase III TP falling MP negative

Critical Observation from Table When TP is at its MAXIMUM (45 units at L=4), MP = ZERO. This is the most tested relationship in exams. After this point, MP becomes negative and TP starts falling.

Section 10

Law of Variable Proportions (LVP) Most Tested — 8 Marks

Statement of the Law The Law of Variable Proportions states that as we increase the quantity of only one variable factor, keeping all other factors fixed, the Total Product (TP) first increases at an increasing rate, then increases at a diminishing (decreasing) rate, and finally decreases (negative rate of growth).

Assumptions of LVP

The law operates in the Short Run only (at least one factor is fixed).
Only one variable factor is changed; all others remain fixed.
Technology is assumed to be constant throughout the analysis.
All units of the variable factor are homogeneous (identical in quality).

What Does LVP Study?

LVP studies the behaviour of Total Product (TP) as we keep increasing the variable factor (e.g., Labour) while the fixed factor (e.g., Machine/Capital) remains unchanged. It shows how output changes in three distinct phases.

Section 11

Three Phases of LVP 8-Mark Answer

Phase I — Increasing Returns (TP rises at Increasing Rate)

Feature	Description
TP Behaviour	Rises rapidly — at an Increasing Rate
MP Behaviour	Rises — MP is increasing (positive and growing)
AP Behaviour	Rises — AP is also increasing
Ends When	MP reaches its maximum point

Reasons for Phase I — Increasing Returns

Better Utilisation of Fixed Factor: The fixed factor (machine) was previously under-utilised. As more labour is added, the machine is put to better use, generating more output per additional worker.
Increased Efficiency of Variable Factor: As more workers join, division of labour and specialisation improve. Each worker becomes more efficient → higher MP.

Phase II — Diminishing Returns (TP rises at Decreasing Rate)

Feature	Description
TP Behaviour	Continues to rise, but at a Diminishing (Decreasing) Rate — growing slowly
MP Behaviour	Falls — MP is decreasing (but still positive, above zero)
AP Behaviour	Also falls in this phase
Ends When	MP becomes Zero (TP reaches its maximum)

Reasons for Phase II — Diminishing Returns

Optimum Combination Reached: The best possible combination of fixed and variable factors has been achieved. The machine is being used at full capacity. Adding more workers cannot improve output at the same rate.
Factors Become Imperfect Substitutes: The variable factor (labour) can no longer substitute for the fixed factor (machine). You need more machines — not more labour. Since machines cannot be added in the short run, additional labour yields less and less.

Producer's Optimal Phase A rational producer will always operate in Phase II. Why? Because TP reaches its maximum in Phase II. Operating in Phase I means you are not reaching full productive potential (wastage of capacity). Operating in Phase III means you are suffering losses (TP actually falls).

Phase III — Negative Returns (TP Falls)

Feature	Description
TP Behaviour	Starts Falling — decreasing absolutely
MP Behaviour	Becomes Negative — additional workers reduce total output
AP Behaviour	Falls but remains positive (AP cannot be negative)
Reason	Severe overcrowding — workers get in each other's way

Reasons for Phase III — Negative Returns

Poor Combination of Fixed and Variable Factors: Too many workers for one machine. Workers are overcrowded and the machine is severely overloaded. The combination is inefficient and counterproductive.
Shortage of Fixed Factor: There is a serious relative shortage of the fixed factor. The fixed factor (machine/capital) simply cannot support so many variable units. Idle workers distract productive workers, reducing total output.

Section 12

TP & MP Diagram Diagram Question

Figure 1 — Total Product (TP) and Marginal Product (MP) Curves — Three Phases of LVP

Upper panel: TP curve (Inverse S-shape) | Lower panel: MP curve (hill-shape then negative) | When TP is maximum → MP = 0

Section 13

Relationship Between TP and MP Most Tested

Phase I — Increasing Returns

TP rises at an Increasing Rate
MP is rising (positive)
MP reaches its maximum at the end of Phase I
Point where MP is max = Point of Inflection of TP

Phase II — Diminishing Returns

TP rises at a Decreasing Rate
MP is falling (positive but declining)
TP reaches its maximum at end of Phase II
When TP = Maximum → MP = Zero

Phase III — Negative Returns

TP falls (decreases absolutely)
MP is negative
AP is falling but remains positive
No rational producer operates here

Key Relationships (All Phases)

TP = Σ MP (Sum of all marginal products)
When MP > 0, TP is increasing
When MP = 0, TP is at maximum
When MP < 0, TP is decreasing

Point of Inflection When a curve changes its nature (e.g., from increasing at an increasing rate to increasing at a decreasing rate), the turning point is called the Point of Inflection. On the TP curve, the point of inflection occurs at the end of Phase I (where TP transitions from rising fast to rising slowly). On the MP curve, the point of inflection is where MP is at its maximum.

Section 14

Law of Diminishing Returns (LDR)

Statement of the Law The Law of Diminishing Returns states that when more and more units of a variable factor are employed with a fixed factor, the Marginal Product (MP) of the variable factor must eventually fall (diminish).

This law is essentially a specific focus on the behaviour of MP (not TP). While the Law of Variable Proportions covers the entire behaviour of TP across all three phases, the Law of Diminishing Returns specifically states that MP will eventually fall as more variable input is added.

Distinction: LVP vs LDR The Law of Variable Proportions describes the entire behaviour of TP (three phases — increasing, diminishing, negative). The Law of Diminishing Returns specifically states that MP will fall when too much variable factor is added. LDR operates within Phase II and Phase III of LVP.

Section 15

Relationship Between AP and MP Important

Core Principle: Average Follows Marginal

Fundamental Rule Average always follows Marginal. When Marginal is greater than Average, Average rises. When Marginal is less than Average, Average falls. When Marginal equals Average, Average is at its maximum.

Cricket Analogy (Exam-Friendly Explanation)

Match	Runs Scored (= MP)	Total Runs (= TP)	Average (= AP)	Observation
1st	50	50	50.0	MP = AP (equal)
2nd	100 ↑ (higher than avg)	150	75.0 ↑	MP > AP → AP rises
3rd	150 ↑	300	100.0 ↑	MP > AP → AP rises
4th	20 ↓ (below avg)	320	80.0 ↓	MP < AP → AP falls

When MP > AP

AP is rising (increasing)
Each additional unit contributes more than the average
Average is being pulled up

When MP = AP

AP is at its Maximum
MP curve intersects (cuts) AP at this point
MP cuts AP at AP's maximum

When MP < AP

AP is falling (decreasing)
Each additional unit contributes less than the average
Average is being pulled down

Special Case — MP Negative

AP can never be negative
MP can become negative in Phase III
AP will continue to fall but stays positive
AP and MP both fall together in Phase II and III

Special Exam Question — Can MP Fall While AP Rises? YES, this is possible. It happens in the zone after MP reaches its maximum (starts falling) but before MP intersects AP at AP's maximum. In this zone, MP is falling but still greater than AP, so AP continues to rise. This is a frequently asked tricky question.

Precise Answer: After MP reaches maximum AND before MP cuts AP (at AP's maximum) — MP is falling but AP is still rising.

Section 16

AP and MP Diagram Diagram Question

Figure 2 — Average Product (AP) and Marginal Product (MP) Curves

MP curve reaches maximum at Q₁ → MP intersects AP at AP's maximum (Q₂) → MP = 0 at Q₃ → MP becomes negative | AP is always above MP once MP starts falling past AP's max

Examination Ready

Most Important Exam Points

All items below are directly relevant to June 2024 and May 2025 question papers.

Core Formulae

TP = Σ MP
AP = TP / Q (variable factor)
MP = ΔTP / ΔQ
MP(n) = TP(n) − TP(n−1)
Q = f(L, K) [Production Function]

TP–MP Relationships

TP rising at ↑ rate → MP rising
TP rising at ↓ rate → MP falling
TP at Maximum → MP = Zero ★
TP falling → MP negative
MP > 0 always → TP is increasing

AP–MP Relationships

MP > AP → AP is rising
MP = AP → AP is at Maximum ★
MP < AP → AP is falling
MP cuts AP at AP's maximum
AP is always positive; MP can be negative

Three Phases — Summary

Phase I: TP↑↑ (increasing rate), MP↑
Phase II: TP↑ (diminishing rate), MP↓
Phase II ends: TP max, MP = 0
Phase III: TP↓, MP negative
Rational producer operates: Phase II

Definitions to Memorise

Short Run: At least one factor fixed
Long Run: All factors variable
Variable Factor: Can be changed in SR
Fixed Factor: Cannot be changed in SR
Usual Fixed Factor: Capital (K)

Reasons for Each Phase

Phase I: Better utilisation of fixed factor + efficiency of variable factor
Phase II: Optimum combination reached + imperfect substitutes
Phase III: Poor combination + shortage of fixed factor

Past-Paper & Likely Questions

Very Important Exam Questions

MCQ — June 2024 Type

______ explains the short-run production: (a) Laws of Returns to Scale (b) Law of Variable Proportion (c) Law of Supply (d) Elasticity of Demand

✓ Answer: (b) Law of Variable Proportion

MCQ — May 2025 Type

When only one factor of production is variable and all other factors are fixed, then it is called: (a) long-run production (b) increasing returns to scale (c) short-run production (d) fixed production

✓ Answer: (c) short-run production

MCQ — May 2025 Type

Change in total product due to one unit change in labour input, keeping other inputs fixed, is called: (a) total product (b) average product (c) marginal product (d) None

✓ Answer: (c) marginal product of labour

MCQ — June 2024 Type

When AP is maximum and constant: (a) MP = AP (b) MR = MC (c) MR = AR (d) all of these

✓ Answer: (a) MP = AP

8-Mark — Theory + Diagram

What are the three stages of production in the Short Run? Draw the graphical representation of these three stages showing TP and MP curves.

→ Define LVP. Draw TP+MP dual panel diagram. Describe all 3 phases with TP and MP behaviour. Give reasons for each phase.

5-Mark — Definitions

Distinguish between Fixed Factors and Variable Factors of production with examples.

→ Define both. Table comparison. Examples: Fixed = Machine/Capital; Variable = Labour, Raw materials. State applicability in short run vs long run.

5-Mark — Factors

What are the factors of production? Briefly explain each.

→ Name all 4: Land, Labour, Capital, Entrepreneurship. Define each with examples. Note: Land = free gift of nature. Entrepreneur = takes risk + seeks profit + innovates.

5-Mark — Numerical

A firm produces 1000 units with 50 labourers and 5 machines. If inputs double to 100 labourers and 10 machines and production becomes 2500 units — what type of return to scale is exhibited and why?

→ Inputs doubled (100%), output increased by 150% (1000→2500). Output grew more than proportionally → Increasing Returns to Scale.

Tricky Theory Question

Can MP fall while AP is still rising? Explain with diagram.

→ YES. After MP reaches maximum but before MP cuts AP at AP's maximum. Show zone on AP-MP diagram. State: MP > AP in this zone so AP still rises.

Short Note

Explain the relationship between AP and MP.

→ Average follows Marginal. MP > AP → AP rises. MP = AP → AP max. MP < AP → AP falls. MP cuts AP at AP's max. AP always positive; MP can be negative. Draw AP-MP diagram.

Last-Minute Revision

Quick Revision Sheet

Production Basics

Production = Conversion of inputs to outputs
Creates utility, NOT matter
4 Factors: Land, Labour, Capital, Enterprise
Land = Free gift of nature

Short Run / Long Run

SR: ≥1 factor fixed
LR: ALL factors variable
SR law: Law of Variable Proportions
LR law: Returns to Scale

TP / AP / MP

TP = Total output
AP = TP / Q (per unit)
MP = ΔTP / ΔQ (extra output)
TP = Σ MP

Phase I

TP ↑↑ (increasing rate)
MP ↑ (rising)
Better utilisation of factors
Ends: MP at maximum

Phase II ★ Optimal

TP ↑ (diminishing rate)
MP ↓ (falling, still +ve)
TP reaches maximum
Ends: MP = 0

Phase III

TP ↓ (falls absolutely)
MP negative
Poor combination of factors
No rational producer here

TP–MP Rules

TP max → MP = 0
TP rising → MP > 0
TP falling → MP < 0
Point of inflection = MP max

AP–MP Rules

MP > AP → AP rises
MP = AP → AP is max
MP < AP → AP falls
AP always positive

Complete Exam-Ready Notes