Forms of Market and Price Determination
This domain asks you to classify markets by number of sellers, product nature and entry conditions, then to derive equilibrium price and output under competition and monopoly. Assam ASSEB questions often combine a market-structure definition with a small demand–supply calculation.
Core rules
- Perfect competition: many buyers and sellers, homogeneous product, free entry and exit, perfect knowledge. The firm is a price taker with horizontal AR = MR; it produces where MR = MC with MC rising and price at least equal to minimum AVC.
- Monopoly: single seller, no close substitute, strong entry barriers. AR slopes down and MR < AR; MR = AR(1 − 1/Ed). A monopolist has no unique supply curve and can earn supernormal profit even in the long run.
- Monopolistic competition: many firms, differentiated products, selling costs, free entry. Downward-sloping AR, normal profit in long-run equilibrium.
- Oligopoly: a few interdependent firms; the kinked demand curve explains price stickiness, so output is indeterminate.
- Market equilibrium occurs where market demand equals market supply. A price ceiling creates shortage; a price floor creates surplus.
Worked example
Qd = 100 − 2P and Qs = 40 + 2P. Setting them equal: 100 − 2P = 40 + 2P, so P = ₹15 and Q = 70 units. At P = ₹20, Qd = 60 and Qs = 80, giving a surplus of 20 units that pushes price back to ₹15.
Traps that cost marks
- Drawing a horizontal demand curve for the industry instead of the firm under perfect competition.
- Claiming a monopolist always charges the highest possible price; it maximises profit where MR = MC, and elasticity limits the markup.
- Attributing selling costs to perfect competition rather than monopolistic competition.
- Forgetting that a monopolist's supply curve does not exist because there is no one-to-one price–quantity relation.