QUESTIONS
1a. "Other thing being equal" Q=f(p)<0. Using appropriate graphs, explain the statement and identify the "other things".
b. The market demand and supply schedules for drinks are given by the following:
Qd = 1000 − 100p
Qs = 500 + 100p
c. Sketch the supply and demand curves and calculate the equilibrium price and quantity.
2. Discuss the importance of the theory of production.
3. Production Isoquant can assume various shapes depending on the degree of substitutability of factors of production. Discuss.
4a. Define what is meant by an Isocost curve.
b. Write explanatory notes on the following:
i. Total physical product.
ii. Average product.
5a. Who is an entrepreneur?
b. What roles does entrepreneur play in an economy?
6a. Why is economics regarded as a science?
b. What are its limitations?
ANSWERS
Question 1
a) "Other things being equal," Q = f(p) < 0
This expression states the Law of Demand: quantity demanded (Q) is a function of price (p), and the relationship is inverse (negative) — as price rises, quantity demanded falls, and vice versa, provided all other factors influencing demand remain constant (the ceteris paribus assumption).
Graphically, this is represented by a downward-sloping demand curve, with price on the vertical axis and quantity on the horizontal axis, sloping from upper-left to lower-right, reflecting the inverse relationship between price and quantity demanded.
The "other things" (ceteris paribus factors) held constant include:
- Income of the consumer
- Prices of related goods (substitutes and complements)
- Consumer tastes and preferences
- Consumer expectations about future prices
- Population/number of buyers in the market
- Advertising and marketing influences
If any of these change, the entire demand curve shifts (rather than a movement along the curve), whereas a change in the price of the good itself causes only a movement along the existing demand curve.
b) & c) Equilibrium price and quantity
Given:
Qd = 1000 − 100p
Qs = 500 + 100p
At equilibrium, Qd = Qs:
1000 − 100p = 500 + 100p
1000 − 500 = 100p + 100p
500 = 200p
p = 2.5
Substituting into Qd:
Q = 1000 − 100(2.5) = 1000 − 250 = 750
Verification using Qs:
Q = 500 + 100(2.5) = 500 + 250 = 750 ✓
Equilibrium price = 2.5; Equilibrium quantity = 750.
The demand curve slopes downward (negative slope, −1/100), the supply curve slopes upward (positive slope, 1/100), and they intersect at the equilibrium point where P = 2.5 and Q = 750, as shown above.
Question 2: Importance of the theory of production
- Guides efficient resource allocation: The theory of production helps firms determine the optimal combination of inputs (land, labour, capital, entrepreneurship) to minimize cost and maximize output.
- Basis for cost analysis: It underlies the derivation of cost curves (total, average, marginal cost), which firms use for pricing and output decisions.
- Explains input substitution: Through concepts such as isoquants and marginal rate of technical substitution, it shows how firms can substitute one factor of production for another while maintaining the same output level.
- Determines profit-maximizing output: By analyzing the relationship between inputs and outputs (production function), firms can identify the output level at which profit is maximized.
- Explains returns to scale: It helps explain how output responds to proportional changes in all inputs (increasing, constant, or decreasing returns to scale), guiding long-run expansion decisions.
- Basis for the law of variable proportions: It explains short-run production behavior when one factor is varied while others are fixed, guiding firms on when to stop adding more of a variable input.
- Aids in policy formulation: Governments and planners use production theory to design policies that promote industrial efficiency and economic growth.
Question 3: Shapes of production isoquants and factor substitutability
An isoquant is a curve showing all the different combinations of two factors of production (typically labour and capital) that yield the same level of output. Its shape depends on the degree of substitutability between the factors:
1. Linear (straight-line) isoquant — perfect substitutes
When factors of production are perfect substitutes for one another, the isoquant is a straight line with a constant slope, implying a constant marginal rate of technical substitution (MRTS). This means one factor can be substituted for the other at a fixed rate without any loss of output (e.g., machines that can perfectly replace certain manual tasks).
2. Right-angled (L-shaped) isoquant — perfect complements (fixed proportions)
When factors must be used in fixed proportions and cannot be substituted for one another at all, the isoquant takes the shape of a right angle (Leontief production function). Output can only increase by increasing both factors together in the fixed ratio; increasing one factor alone without the other adds nothing to output.
3. Convex (smooth, bowed-in) isoquant — imperfect substitutes
This is the most common and realistic case, where factors can substitute for one another but not perfectly. The isoquant is convex to the origin, and the MRTS diminishes as one factor is substituted for the other — meaning progressively more units of one factor are needed to replace a unit of the other while maintaining the same output level, reflecting diminishing marginal productivity.
4. Kinked isoquant
In some cases, isoquants may have a kinked shape, representing limited substitutability at specific ranges — factors are substitutable at certain combinations but not smoothly at every point, often used in linear programming applications of production.
Conclusion: The shape of the isoquant reflects the technical feasibility of substituting one input for another; the higher the degree of substitutability, the flatter and closer to a straight line the isoquant becomes, while lower substitutability produces a more sharply convex or right-angled curve.
Question 4
a) Isocost curve
An isocost curve (or isocost line) shows all the possible combinations of two factors of production (e.g., labour and capital) that a firm can purchase for a given total cost outlay, given the prices of the factors. It is represented as a straight line, with its slope equal to the negative ratio of the factor prices (−Pl/Pk), and its position determined by the firm's total budget and the prices of the inputs. A change in the total budget shifts the isocost line parallel to itself, while a change in the relative price of one factor changes its slope.
b) i) Total physical product (TPP)
Total physical product refers to the total quantity of output produced by a firm using a given combination of factors of production, typically shown as the amount produced when a variable factor (e.g., labour) is combined with fixed factors. As more units of the variable factor are added, TPP initially increases at an increasing rate, then at a decreasing rate, and eventually may decline, in accordance with the law of variable proportions.
b) ii) Average product (AP)
Average product refers to the output produced per unit of the variable factor of production, calculated as:
AP = Total Physical Product (TPP) ÷ Quantity of variable factor used
It measures the productivity of each unit of the variable input on average and typically rises initially, reaches a maximum, and then declines as more units of the variable factor are added to fixed factors, consistent with the law of diminishing returns.
Question 5
a) Who is an entrepreneur?
An entrepreneur is an individual who organizes, manages, and assumes the risk of a business enterprise, combining the other factors of production (land, labour, and capital) to produce goods and services with the aim of making a profit. The entrepreneur is often characterized by innovation, risk-bearing, and decision-making ability in the pursuit of business opportunities.
b) Roles of an entrepreneur in an economy
- Organization of production: The entrepreneur combines and coordinates the other factors of production (land, labour, capital) to produce goods and services efficiently.
- Risk-bearing: The entrepreneur bears the uncertainty and risk of business, including the possibility of loss, in anticipation of profit.
- Innovation: Entrepreneurs introduce new products, production techniques, and business methods, driving technological progress and economic development.
- Employment generation: By establishing and expanding businesses, entrepreneurs create job opportunities for others in the economy.
- Wealth and income creation: Entrepreneurial activities generate income for the entrepreneur, employees, and government (through taxation), contributing to overall economic growth.
- Capital formation: Entrepreneurs mobilize savings and investment into productive ventures, contributing to capital accumulation in the economy.
- Decision-making: The entrepreneur makes crucial business decisions regarding what to produce, how to produce, and for whom to produce.
Question 6
a) Why economics is regarded as a science
Economics is regarded as a science because:
- It employs systematic methods of inquiry, involving observation, hypothesis formulation, and testing, similar to the natural sciences.
- It uses logical and quantitative tools, including mathematical models, statistics, and graphs, to analyze economic phenomena.
- It formulates general laws and principles (e.g., the law of demand, law of diminishing returns) based on observed regularities in economic behavior.
- It makes predictions about economic behavior and outcomes based on established theories and models, which can be tested against real-world data.
- It is objective in its analysis, seeking to explain "what is" (positive economics) using verifiable evidence, rather than merely stating opinions.
b) Limitations of economics as a science
- Human behavior is unpredictable: Unlike physical sciences, economics deals with human behavior, which is influenced by emotions, psychology, and social factors that are difficult to predict with precision.
- Difficulty of controlled experiments: Economics largely cannot conduct controlled laboratory experiments as in the physical sciences; it relies on real-world observation, where many variables change simultaneously.
- Value judgments: Economic policy recommendations (normative economics) often involve subjective value judgments about what "ought to be," which cannot be scientifically proven right or wrong.
- Ceteris paribus limitation: Economic laws are often based on the assumption "other things being equal," which rarely holds true in the real world, limiting the precision of predictions.
- Lack of exact measurement: Many economic variables (e.g., utility, welfare, satisfaction) are difficult to measure precisely, unlike physical quantities in the natural sciences.
- Influence of non-economic factors: Economic outcomes are often influenced by political, social, cultural, and historical factors that fall outside the scope of pure economic analysis.