1. Use the arc-approximation formula to calculate the price elasticity of the demand coefficient of a firm's product demand between the (quantity, price) points of (12, $20) and (18, $16).
2. Calculate the cross-price elasticity of the demand coefficient of a firm's product X, given that a 10% increase in the price of its close substitute, product Y, causes the quantity demand of product X to increase by 6%.
3. Calculate the income elasticity of the demand coefficient for a product for which a 5% increase in consumers' income will increase the quantity demanded by 4%.

4. Why do most countries have some protectionist trade barriers?

5. Identify two types of protectionist trade barriers.

6. Which is usually better for most countries, protectionist trade policies or free trade? Explain.

7. For most countries would a fair trade policy usually be the same as a free trade policy? Explain.