Micro Economics Basics Questions for SSC CGL

Law of Demand and Supply

The law of demand states that as price increases, quantity demanded decreases (and vice versa), assuming all other factors remain constant. This inverse relationship is the foundation of microeconomics. The law of supply is the opposite: as price rises, suppliers are willing to produce more. The point where demand and supply curves intersect is the equilibrium price and quantity — the market-clearing point where no shortage or surplus exists.

• Demand curve slopes downward (left to right); supply curve slopes upward
• Equilibrium occurs where Qd = Qs; any deviation causes price adjustment
• Shift in demand/supply (due to income, tastes, technology) moves the entire curve, not just a point on it
• Movement along a curve = change in price of that good; shift of curve = change in external factors
• Shortage (Qd > Qs) pushes price up; surplus (Qs > Qd) pushes price down

Price Elasticity of Demand (PED)

Elasticity measures how sensitive quantity demanded is to a price change. If PED > 1, demand is elastic (quantity changes more than price); if PED < 1, demand is inelastic (quantity changes less than price); if PED = 1, demand is unit elastic. Goods with few substitutes (salt, medicines) are inelastic; goods with many substitutes (brands of cereal) are elastic. This concept is heavily tested in SSC CGL because it explains real-world pricing strategies.

• Elastic demand: consumers very responsive to price; lower price increases total revenue
• Inelastic demand: consumers less responsive; higher price increases total revenue
• Determinants: availability of substitutes, necessity vs luxury, proportion of income spent, time horizon
• Luxury goods = elastic; necessities = inelastic
• Cross elasticity measures responsiveness to price of another good (substitutes vs complements)

Consumer and Producer Surplus

Consumer surplus is the difference between what a consumer is willing to pay and what they actually pay — it represents the benefit or gain from a purchase. Producer surplus is the difference between the price received and the minimum price a producer is willing to accept — it represents profit above cost. Both are maximized at equilibrium. These concepts explain why markets are efficient and why price controls (like price ceiling or floor) create deadweight loss.

• Consumer surplus = area above price line and below demand curve
• Producer surplus = area below price line and above supply curve
• Price ceiling (max price set by government) reduces both surpluses and creates shortage
• Price floor (min price set by government) reduces both surpluses and creates surplus of goods
• Total surplus = consumer surplus + producer surplus; maximized at equilibrium

Market Structures: Perfect Competition vs Monopoly

Perfect competition has many firms, homogeneous products, free entry/exit, and price-taker behavior. Firms earn zero economic profit in long run. Monopoly has one firm, unique product, high barriers to entry, and price-maker behavior. Monopolist can earn supernormal profit. SSC CGL often asks to distinguish these or identify characteristics. Oligopoly (few large firms) and monopolistic competition (many firms, differentiated products) are intermediate structures.

• Perfect competition: P = MC (price equals marginal cost); allocatively efficient
• Monopoly: P > MC; produces less, charges more; allocatively inefficient but may have economies of scale
• Perfect competition: many sellers, homogeneous goods, free entry; monopoly: one seller, unique good, barriers
• Oligopoly: few firms, interdependent decisions, may collude (cartel) to maximize profit
• Monopolistic competition: many firms, differentiated products, some pricing power but long-run zero profit

Production and Cost Concepts

Total Cost (TC) = Fixed Cost (FC) + Variable Cost (VC). Fixed costs don't change with output (rent, salaries); variable costs change with output (raw materials, wages). Average Cost (AC) = TC / Quantity; Marginal Cost (MC) = change in TC / change in Quantity. The MC curve intersects the AC curve at its minimum point. Firms maximize profit where MC = MR (marginal revenue). Understanding cost behavior is crucial for understanding firm decisions.

• Fixed cost remains constant; variable cost increases with production
• Average cost initially falls (due to spreading FC), then rises (due to diminishing returns)
• Marginal cost = additional cost of producing one more unit
• Profit-maximizing output: MC = MR (marginal revenue)
• Shutdown point: if price < minimum AVC, firm should stop production in short run

Utility and Consumer Behavior

Utility is the satisfaction a consumer derives from consuming a good. Total utility increases with consumption but at a decreasing rate (diminishing marginal utility). Marginal utility is the additional satisfaction from one more unit. Rational consumers maximize utility by equating marginal utility per rupee spent across all goods. This explains why consumers buy diverse goods rather than just one item.

• Marginal utility diminishes as consumption increases (law of diminishing marginal utility)
• Consumer equilibrium: MU of good A / Price A = MU of good B / Price B
• If MU/Price ratio is higher for one good, consumer should buy more of that good
• Indifference curve shows combinations of two goods giving same utility
• Budget line shows affordable combinations; consumer optimum is where budget line is tangent to indifference curve

• Confusing movement along demand curve (price change) with shift of demand curve (external factor change like income). SSC often tests this distinction.
• Thinking elastic demand means high price — it actually means quantity is very responsive to price, so lower price increases revenue. Opposite for inelastic.
• Assuming perfect competition always exists — most real markets are monopolistic competition or oligopoly. SSC asks to identify market type from characteristics.
• Forgetting that in perfect competition, long-run profit is zero because free entry drives price down to AC. Monopoly can sustain supernormal profit.
• Mixing up consumer surplus (buyer's benefit) with producer surplus (seller's benefit). They are on opposite sides of the equilibrium price.

• DEMAND DOWN, SUPPLY UP: Demand curve slopes down (inverse relationship with price); supply curve slopes up (direct relationship). Think: higher price attracts suppliers but repels buyers.
• ELASTIC = STRETCHY: Elastic demand stretches a lot when price changes (like a rubber band). Inelastic is stiff (like a steel rod) — doesn't stretch much.
• PED > 1 = ELASTIC; PED < 1 = INELASTIC: Remember '1' as the dividing line. Above 1 = elastic; below 1 = inelastic.
• MC = MR for PROFIT MAX: Firms stop expanding when marginal cost equals marginal revenue. Beyond that point, cost exceeds benefit.
• PERFECT = ZERO PROFIT: In perfect competition, long run = zero economic profit. Monopoly = supernormal profit. Opposite structures, opposite outcomes.

• SSC CGL typically asks 2-3 definition-based questions: 'Which of the following is true about elasticity?' or 'In perfect competition, firms are...' Focus on identifying characteristics, not calculations.
• Graph-reading questions are common: given a demand-supply diagram, identify equilibrium, shortage, or surplus. Practice interpreting shifts vs movements.
• Price ceiling/floor questions appear frequently in recent papers. Remember: ceiling creates shortage, floor creates surplus. Both reduce total surplus.
• Monopoly vs perfect competition comparison is a high-frequency question type. Know the 5-6 key differences (number of firms, entry barriers, profit, price-setting power).
• Cost concepts (FC, VC, AC, MC) are tested but rarely require calculation in SSC CGL — mostly conceptual understanding. Know which cost is relevant for shutdown decision (AVC, not AC).
• Time management: these questions are quick if you know definitions. Spend max 1 minute per question; don't get stuck on graph interpretation.