经济学原理·萨缪尔森--中山大学岭南学院ch(5).ppt

Part Two,Microeconomics: Supply, Demand and Product Market,Ch4. Applications of supply and demand,需求与供给的应用,A. Elasticity of demand and supply,需求与供给弹性,Price elasticity of demand,需求的价格弹性： (price elasticity): measuring how much the quantity demanded of a good changes when its price changes.,ED=(percentage change in quantity demanded )/percentage change in price.,Elastic Demand Shows Large Quantity Response to Price Change,Categories of price elasticity:,价格弹性的分类： price-elastic demand: ED 1 price-inelastic demand: ED 1 unit-elastic demand: ED =1,Price Elasticity of Demand Falls into Three Categories,Formula for elasticity:,Special case: Linear demand curve:,Linear demand curve:,elasticity is high at top, low at bottom, exactly 1 in the middle.,Perfectly Elastic and Inelastic Demands,A Simple Rule for Calculating the Demand Elasticity,Total Revenue(TR)=PQ,When ED 1, P PQ When ED =1, P PQ constant,Price elasticity of Supply,供给的价格弹性： ES=(percentage change in quantity supplied )/percentage change in price.,Supply Elasticity Depends upon Producer Response to Price,B. Applications to Major Economic Issues,Prices of Basic Farm Products Have Declined Sharply,Agricultural Distress Results from Expanding Supply and Price-Inelastic Demand,The economic of agriculture:,Price support（价格支持） Tariffs and Quotas（关税与配额） not to Produce Crop restriction,Crop-Restriction Program Raise both Price and Farm Income,Impact of a tax on price and quantity:,The incidence of a tax: consumers and producers. The relationship of tax and elasticity:,Gasoline Tax Falls on Both Consumer and Producer,Impact of a Subsidies on price and quantity,补贴对价格与数量的影响,Minimum floors and maximum ceilings:,最高限价与最低限价 Minimum wage: unemployment Energy price controls: shortage,The Minimum Wage and