1. ความยืดหยุ่น การประยุกต์ใช้ความยืดหยุ่น และประสิทธิภาพของระบบตลาด ดร . รพีสุภา หวังเจริญรุ่ง

10. Figure 1 The Price Elasticity of Demand Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning (a) อุปสงค์ไม่ยืดหยุ่นเลย (Perfectly Inelastic Demand): Ed = 0 Quantity 0 Price $5 4 Demand 100 1. An increase in price . . . 2. . . . leaves the quantity demanded unchanged.

11. Figure 1 The Price Elasticity of Demand Thai Economy in Global Context 2- (b) อุปสงค์ยืดหยุ่นน้อย (Inelastic Demand): Ed < 1 Quantity 0 Price $5 90 Demand 1. A 22% increase in price . . . 2. . . . leads to an 11% decrease in quantity demanded. 4 100

12. Figure 1 The Price Elasticity of Demand Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning (c) อุปสงค์ยืดหยุ่นคงที่ ( Unit Elastic Demand): Ed = 1 Quantity 0 Price 2. . . . leads to a 22% decrease in quantity demanded. 4 100 $5 80 1. A 22% increase in price . . . Demand

13. Figure 1 The Price Elasticity of Demand Thai Economy in Global Context 2- (d) อุปสงค์มีความยืดหยุ่นมาก ( Elastic Demand): Ed > 1 Quantity 0 Price Demand 4 100 $5 50 1. A 22% increase in price . . . 2. . . . leads to a 67% decrease in quantity demanded.

14. Figure 1 The Price Elasticity of Demand Thai Economy in Global Context 2- (e) อุปสงค์ยืดหยุ่นอย่างสมบูรณ์ ( Perfectly Elastic Demand): E = Quantity 0 Price $4 Demand 2. At exactly $4, consumers will buy any quantity. 1. At any price above $4, quantity demanded is zero. 3. At a price below $4, quantity demanded is infinite.

16. Figure 2 รายรับรวม (Total Revenue: TR) Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning Quantity 0 Price Demand Q P P × Q = $400 (revenue) $4 100

17. Figure 3 รายรับรวม (TR) เปลี่ยนแปลงอย่างไรเมื่อราคาเปลี่ยนแปลง : อุปสงค์ยืดหยุ่นน้อย (Inelastic Demand) Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning Quantity 0 Price Quantity 0 Price An Increase in price from $1 to $3 … … leads to an Increase in total revenue from $100 to $240 Demand Revenue = $100 Revenue = $240 Demand $1 100 $3 80

18. Figure 4 รายรับรวม (TR) เปลี่ยนแปลงอย่างไรเมื่อราคาเปลี่ยนแปลง : อุปสงค์ยืดหยุ่นมาก (Elastic Demand) Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning Quantity 0 Price Quantity 0 Price An Increase in price from $4 to $5 … … leads to an decrease in total revenue from $200 to $100 Demand Revenue = $200 $4 50 Demand Revenue = $100 $5 20

20. ตัวอย่าง Elasticity of a Linear Demand Curve Thai Economy in Global Context 2-

25. Figure 6 The Price Elasticity of Supply Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning (a) อุปทานไม่ยืดหยุ่นเลย (Perfectly Inelastic Supply): Es = 0 Quantity 100 0 Price $5 4 Supply 1. An increase in price . . . 2. . . . leaves the quantity supplied unchanged.

26. Figure 6 The Price Elasticity of Supply Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning (b) อุปทานยืดหยุ่นน้อย ( Inelastic Supply): Es < 1 Quantity 0 Price 110 $5 100 4 1. A 22% increase in price . . . 2. . . . leads to a 10% increase in quantity supplied. Supply

27. Figure 6 The Price Elasticity of Supply Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning (c) อุปทานยืดหยุ่นคงที่ ( Unit Elastic Supply): Es = 1 Quantity 0 Price 125 $5 100 4 2. . . . leads to a 22% increase in quantity supplied. 1. A 22% increase in price . . . Supply

28. Figure 6 The Price Elasticity of Supply Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning (d) อุปทานยืดหยุ่นมาก ( Elastic Supply): Es > 1 Quantity 0 Price 1. A 22% increase in price . . . 2. . . . leads to a 67% increase in quantity supplied. 4 100 $5 200 Supply

29. Figure 6 The Price Elasticity of Supply Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning (e) อุปทานยืดหยุ่นอย่างสมบูรณ์ ( Perfectly Elastic Supply): Es = Quantity 0 Price $4 Supply 3. At a price below $4, quantity supplied is zero. 2. At exactly $4, producers will supply any quantity. 1. At any price above $4, quantity supplied is infinite.

35. Table 1 Four Possible Buyers’ Willingness to Pay Thai Economy in Global Context 2- Copyright©2004 South-Western

36. ตารางอุปสงค์ และเส้นอุปสงค์ Thai Economy in Global Context 2-

37. Figure 7 The Demand Schedule and the Demand Curve Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning Price of Album 0 Quantity of Albums 1 2 3 4 Demand $100 John ’ s willingness to pay 80 Paul ’ s willingness to pay 70 George ’ s willingness to pay 50 Ringo ’ s willingness to pay

38. Figure 8 Measuring Consumer Surplus with the Demand Curve Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning (a) Price = $80 Price of Album 50 70 80 0 $100 1 2 3 4 Quantity of Albums Demand John ’ s consumer surplus ($20)

39. Figure 8 Measuring Consumer Surplus with the Demand Curve Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning (b) Price = $70 Price of Album 50 70 80 0 $100 1 2 3 4 Quantity of Albums Demand Total consumer surplus ($40) John ’ s consumer surplus ($30) Paul ’ s consumer surplus ($10)

41. Figure 9 How the Price Affects Consumer Surplus Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning Quantity (a) Consumer Surplus at Price P Price 0 Consumer surplus Demand P 1 Q 1 B A C

42. Figure 9 How the Price Affects Consumer Surplus Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning Quantity (b) Consumer Surplus at Price P Price 0 Initial consumer surplus Demand A B C D E F P 1 Q 1 P 2 Q 2 Consumer surplus to new consumers Additional consumer surplus to initial consumers

44. Table 2 The Costs of Four Possible Sellers Thai Economy in Global Context 2- Copyright©2004 South-Western

45. ตารางอุปทาน และเส้นอุปทาน Thai Economy in Global Context 2-

46. Figure 10 The Supply Schedule and the Supply Curve Thai Economy in Global Context 2-

47. Figure 11 Measuring Producer Surplus with the Supply Curve Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning Quantity of Houses Painted Price of House Painting 500 800 $900 0 600 1 2 3 4 (a) Price = $600 Supply Grandma ’ s producer surplus ($100)

48. Figure 11 Measuring Producer Surplus with the Supply Curve Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning Quantity of Houses Painted Price of House Painting 500 800 $900 0 600 1 2 3 4 (b) Price = $800 Georgia ’ s producer surplus ($200) Total producer surplus ($500) Grandma ’ s producer surplus ($300) Supply

49. Figure 12 How the Price Affects Producer Surplus Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning Quantity (a) Producer Surplus at Price P Price 0 Producer surplus Supply B A C Q 1 P 1

50. Figure 12 How the Price Affects Producer Surplus Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning Quantity (b) Producer Surplus at Price P Price 0 P 1 B C Supply A Initial producer surplus Q 1 P 2 Q 2 Producer surplus to new producers Additional producer surplus to initial producers D E F

55. Figure 13 Consumer and Producer Surplus in the Market Equilibrium Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning Price 0 Quantity Producer surplus Consumer surplus Equilibrium price Equilibrium quantity Supply Demand A C B D E

57. Figure 14 The Efficiency of the Equilibrium Quantity Thai Economy in Global Context 2- Copyright©2003 Southwestern/Thomson Learning Quantity Price 0 Supply Demand Cost to sellers Cost to sellers Value to buyers Value to buyers Value to buyers is greater than cost to sellers. Value to buyers is less than cost to sellers. Equilibrium quantity