Chapter 3 A Demand B.Supply C. Equilibrium of supply and demand D. A change of equilibrium 1 2023/7/17 Economics
1 2023/7/17 Economics Chapter 3 A. Demand B. Supply C. Equilibrium of supply and demand D. A change of equilibrium
A.Demand Demand and the quantity demanded A change in demand and a change in the quantity demanded Main influences on demand 2 2023/7117 Economics
2 2023/7/17 Economics A. Demand ◼ Demand and the quantity demanded ◼ A change in demand and a change in the quantity demanded ◼ Main influences on demand
The law of demand The law of demand:the quantity demanded for a commodity is negatively related to its price-as the price rises,the quantity demanded decreases and as the price falls,the quantity demanded increases.(and other things are held constant)(P48) The demand function or equation: Qd=f(p),dQ dP0. ■The demand curve ■The demand schedule 3 2023/7117 Economics
3 2023/7/17 Economics The law of demand ◼ The law of demand: the quantity demanded for a commodity is negatively related to its price—as the price rises,the quantity demanded decreases and as the price falls,the quantity demanded increases. (and other things are held constant)(P48) ◼ The demand function or equation: Qd=f(p), dQ／dP0. ◼ The demand curve ◼ The demand schedule
Figure3-1 The demand curve 4 2023/7/17 Economics
4 2023/7/17 Economics Figure3-1 The demand curve P o Q D
Table3-1 Demand schedule for cornflakes(玉米片) Price Quantity ($per box) demanded(millions of boxes per year) A 5 9 B 4 10 C 3 12 D 2 15 E 1 20 5 2023/7117 Economics
5 2023/7/17 Economics Table3-1 Demand schedule for cornflakes（玉米片） Price ($per box) Quantity demanded(millions of boxes per year) A 5 9 B 4 10 C 3 12 D 2 15 E 1 20
A change in demand and a change in the quantity demanded ■A change in demand denotes a shift of the o demand curve. D2 A change in the a p quantity demanded represents a b P2 movement along the demand curve. Q1 Q2 Q 6 2023/7117 Economics
6 2023/7/17 Economics A change in demand and a change in the quantity demanded ◼ A change in demand denotes a shift of the demand curve. ◼ A change in the quantity demanded represents a movement along the demand curve. o Q D2 D0 D1 a b p1 p2 Q1 Q2 P
Main influences on demand(or factors affecting the demand curve)(P50) 1.A change of the number of people(population) 2.A change in income Normal goods(正常商品) Inferior goods(劣等商品) 3.Changes in the prices of related goods substitutes(替代商品)are the products that satisfy the same needs. complements(互补商品)are the products that satisfy a need together with some other products. 4.A change in the likes or dislikes(tastes,preference 偏好) 5.Expectations of future price and income 7 20237117 Economics
7 2023/7/17 Economics Main influences on demand(or factors affecting the demand curve)(P50) 1.A change of the number of people(population) 2.A change in income Normal goods（正常商品） Inferior goods（劣等商品） 3.Changes in the prices of related goods substitutes（替代商品）are the products that satisfy the same needs. complements（互补商品）are the products that satisfy a need together with some other products. 4.A change in the likes or dislikes (tastes,preference 偏好) 5. Expectations of future price and income
B.supply supply and the quantity supplied A change in supply and a change in the quantity supplied Main influences on supply 8 2023/7117 Economics
8 2023/7/17 Economics B. supply ◼ supply and the quantity supplied ◼ A change in supply and a change in the quantity supplied ◼ Main influences on supply
The law of supply The law of supply:the quantity supplied for a commodity is positively related to its price-as the price rises,the quantity supplied increases and as the price falls,the quantity supplied decreases.(and other things are held constant) The supply function or equation: Qs=f(p),dQ dP>0. Qs=c dP,d>0. ■The supply curve ■The supply schedule 9 2023/7117 Economics
9 2023/7/17 Economics The law of supply ◼ The law of supply: the quantity supplied for a commodity is positively related to its price—as the price rises,the quantity supplied increases and as the price falls,the quantity supplied decreases. (and other things are held constant) ◼ The supply function or equation: Qs=f(p), dQ／dP>0. Qs=c + dP, d>0. ◼ The supply curve ◼ The supply schedule
Figure3-2 The supply curve 0 Q 10 2023/7117 Economics
10 2023/7/17 Economics Figure3-2 The supply curve P o Q S