(a) Consider the market for good X for Country 1 and Country 2. The supply and demand functions for Country 1 are given as P = Q…

(a) Import quota and import tariff: Country 1 as the importer

Autarky. Country 1: P = Q + 70 and P = 170 − Q give P = 120, Q = 50. Country 2: P = 10 + Q and P = 110 − Q give P = 60, Q = 50. So Country 1 imports and Country 2 exports.

Free trade. Country 1's import demand = (170 − P) − (P − 70) = 240 − 2P. Country 2's export supply = (P − 10) − (110 − P) = 2P − 120. Balanced trade needs 240 − 2P = 2P − 120, so the free-trade price is ₹90, and trade is 60 units. Country 1 then consumes 80 units and produces 20, so consumer surplus = ½ × (170 − 90) × 80 = ₹3,200 and producer surplus = ½ × (90 − 70) × 20 = ₹200.

(i) Import quota of 50 units. Domestic supply plus 50 must equal demand: (P − 70) + 50 = 170 − P, so the domestic price is ₹95. Quantity consumed = 170 − 95 = 75 units and quantity produced = 95 − 70 = 25 units. Consumer surplus = ½ × (170 − 95) × 75 = ₹2,812.50 (a fall of ₹387.50) and producer surplus = ½ × (95 − 70) × 25 = ₹312.50 (a rise of ₹112.50).

The exporter must sell only 50 units, so its price falls to ₹85 (2P − 120 = 50). The quota rent = (95 − 85) × 50 = ₹500.

Protection cost (deadweight loss), measured against the free-trade price: production distortion = ½ × (25 − 20) × (95 − 90) = ₹12.50, and consumption distortion = ½ × (80 − 75) × (95 − 90) = ₹12.50, so the total is ₹25. If the quota rent of ₹500 is captured at home, through auctioned licences, the country also gains from the lower import price (₹85 instead of ₹90 on 50 units, or ₹250), and net welfare change is −387.50 + 112.50 + 500 = +₹225 (that is, −25 + 250). If the rent goes to foreigners, the country loses ₹275 in surplus.

(ii) Import tariff of ₹10 by a small country. The world price stays at ₹90, so the domestic price is ₹100. Consumption = 170 − 100 = 70 units; production = 100 − 70 = 30 units; imports = 40 units. Consumer surplus = ½ × 70 × 70 = ₹2,450, a fall of ₹750. Producer surplus = ½ × 30 × 30 = ₹450, a rise of ₹250. Government revenue = 10 × 40 = ₹400. Net welfare = −750 + 250 + 400 = −₹100, which equals the deadweight loss of ½ × 10 × 10 + ½ × 10 × 10 = ₹100 (production ₹50 and consumption ₹50). The tariff does not raise national welfare; it lowers it by ₹100, because a small country cannot improve its terms of trade.

(b) Innovation and trade between similar countries

The statement is largely valid. The Heckscher-Ohlin theory predicts little trade between countries with similar factor endowments and tastes, since comparative advantage arises from differences. Innovation-based theories explain trade without such differences.

Posner's technology-gap theory says a country that innovates first has a temporary advantage in the new product and exports it until imitation closes the gap. Vernon's product cycle shows the pattern: new goods are made in the innovating country, then in other advanced countries, and then in lower-cost countries, while continuing innovation creates new exports. So trade is continuous and dynamic.

Innovation also creates product differentiation. With economies of scale and monopolistic competition, firms in similar countries make different varieties and trade them, giving intra-industry trade, as among the US, Europe and Japan in machinery and electronics. Linder's overlapping-demand argument adds that similar incomes and tastes favour trade in differentiated manufactures.

Qualifications: innovation-led trade needs intellectual property protection, research capacity, and market size, and imitation reduces the gap over time. Comparative advantage still explains much inter-industry trade, for example between developed and developing countries. The statement thus complements, rather than replaces, factor-endowment theory.

(c) External economies and product variety in international trade theory

External economies are cost savings that arise at the level of the industry, not the firm, from a pool of skilled labour, specialised suppliers and knowledge spillovers. They give increasing returns at the industry level while firms stay small and competitive. Their significance for trade is that comparative advantage can be acquired, not only inherited: a country that becomes the centre of an industry, such as software in Bangalore or diamond cutting in Surat, gets lasting cost advantage. Trade can then be based on history and accident, there can be multiple equilibria, and a temporary policy intervention may shift the pattern, which is the argument for strategic trade policy, although it is difficult to choose winners.

Product variety is central to the new trade theory of Krugman and the Dixit-Stiglitz model. Consumers value variety, and firms differentiate products under scale economies. Trade enlarges the market, so each firm can produce at a lower average cost, while consumers get a wider range. This explains intra-industry trade between similar countries and a gain from trade beyond comparative advantage. Melitz adds that trade shifts resources to the more productive firms, raising industry productivity.

Limitations: external economies may be local and not certain; adjustment costs and loss of some domestic varieties can occur; and gains depend on market size and trade openness.