Country A can produce 20 widgets OR 10 gadgets per hour. Country B can produce 6 widgets OR 6 gadgets per hour. Which statement correctly identifies comparative advantage?
ACountry A has comparative advantage in both goods because it produces more of each
BCountry B has comparative advantage in gadgets because its opportunity cost (1 widget per gadget) is lower than Country A's (2 widgets per gadget)
CCountry B has no basis for trade since Country A is more productive at everything
DComparative advantage cannot be determined without knowing the countries' total populations
Comparative advantage is about opportunity cost, not total output. Country A gives up 2 widgets to produce 1 gadget; Country B gives up only 1 widget per gadget. So Country B has the comparative advantage in gadgets despite being less productive overall. Country A gives up only 0.5 gadgets per widget (vs. B's 1 gadget per widget), so A has the comparative advantage in widgets. Option A is the classic confusion between absolute advantage (producing more) and comparative advantage (lower opportunity cost).
Question 2 Multiple Choice
Country Z is less efficient at producing every single good than Country W. What follows from this?
ACountry Z cannot benefit from trading with Country W since it has no absolute advantage
BCountry Z still has a comparative advantage in whichever good it is relatively least inefficient at producing
CCountry W should refuse to trade with Country Z to protect its productive superiority
DTrade is impossible when one party has an absolute advantage in all goods
This is the most important insight of comparative advantage: no country is ever 'priced out' of trade. Because comparative advantage is defined by relative opportunity costs, if Country Z is somewhat less bad at producing Good A than Good B, it has a comparative advantage in A — and Country W necessarily has a comparative advantage in B. The two countries' opportunity costs must differ (unless they're identical, which is the one case where trade offers no gain). Having no absolute advantage never means having no comparative advantage.
Question 3 True / False
A country can hold comparative advantage in multiple goods simultaneously if it is significantly more efficient at producing most of them.
TTrue
FFalse
Answer: False
Comparative advantage is a relative concept that is zero-sum within a pair of goods: if your opportunity cost of producing Good A is lower than your trading partner's, your opportunity cost of producing Good B must be higher. It is mathematically impossible to have a comparative advantage in all goods against the same partner. This is what distinguishes comparative advantage from absolute advantage — you can have absolute advantage in everything, but you can never have comparative advantage in everything.
Question 4 True / False
Specialization according to comparative advantage allows both trading partners to consume combinations of goods that neither could produce on its own.
TTrue
FFalse
Answer: True
This is the key payoff of comparative advantage theory. When each producer specializes in the good where their opportunity cost is lowest, total production of both goods increases. Trading at a price ratio between the two parties' opportunity costs lets each party consume beyond its own PPF. Trade acts as a technology: it expands consumption possibilities without changing productive capacity.
Question 5 Short Answer
Why does the distinction between absolute advantage and comparative advantage matter for predicting whether two parties will benefit from trade?
Think about your answer, then reveal below.
Model answer: Absolute advantage — being able to produce more output — does not determine whether trade is mutually beneficial. What matters is comparative advantage: whether the parties have different opportunity costs for producing the two goods. As long as opportunity costs differ, both parties gain by specializing in the good where their opportunity cost is lower and trading for the other. If one party had to have absolute advantage for trade to benefit both, no economically weaker country would ever trade — but in practice all countries gain from trade because comparative advantage always exists when opportunity costs differ.
The distinction collapses the intuition that 'stronger always wins.' Even a highly productive country benefits from trading for goods where its opportunity cost is high, because doing so frees its resources for goods where its opportunity cost is low. The country it trades with captures the same logic from the other direction.