ความยืดหยุ่นของอุปสงค์ (elasticity of demand)

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  1. 1. .. (Elasticity of Demand : Ed)
  2. 2. (Elasticity of Demand) = % %
  3. 3. (Elasticity of Demand) 2 10 ................
  4. 4. (Elasticity of Demand) 30 80 ................
  5. 5. (Elasticity of Demand) 3 1. (price elasticity of demand : Ep) 2. (income elasticity of demand : Ei) 3. (cross price elasticity of demand : Ec)
  6. 6. 2 1. Point Elasticity () (X) Elasticity = % Q = dQ/Q1 = dQ . X1 Q x X1 2. Arc Elasticity () (X) Elasticity = % Q = dQ/[(Q1+Q2)/2] = dQ . (X1+X2) = Q x (X1+X2) % X dX/X1 dX Q1 % X dX/[(X1+X2)/2] dX (Q1+Q2) X (Q1+Q2) X Q1
  7. 7. (Ep) (Price Elasticity of Demand)
  8. 8. (Ep) (Price Elasticity of Demand) Ep 1 Ep = % 1. Point Elasticity () Ep = (Q2-Q1) . P1 2. Arc Elasticity () Ep = (Q2-Q1) . (P1+P2) (P2-P1) Q1 (P2-P1) (Q1+Q2) %
  9. 9. Ex1 3 5 15 10 Ep
  10. 10. Ex2 5 3 10 15 Ep
  11. 11. Ex3 Ep A 2
  12. 12. Ep() = -CQ = -OP OQ BP Point Elasticity () Ep = (Q2-Q1) . P1 (P2-P1) Q1 P Q Q P
  13. 13. () A B D (P) (Q)0 240 10 200 Q1 Q2 P1 P28 Slope (-) Ep 10 (-) 1 Ep 8 (-) 0.67 Ep 8 10 (-) 0.81
  14. 14.
  15. 15. () (|Ed| > 1) (|Ed| < 1)
  16. 16. () 50% 3 /?. Ep>1 Ep1 Ep1 Ep 1 Ed = 1 Ed < 1 Slope (-) D
  17. 25. 2. (P) (Q)0 10 5 20 DA DB Slope = - 3, Ed = -0.67 Slope = - 2, Ed = -0.25 !!!
  18. 26. ( ) (P) (Q)0 10 10 DA DB Slope = - 2, Ed = -0.5 Slope = - 4, Ed = -0.25 !!!
  19. 27.
  20. 28. Ep (perfEitly elastic) Ep= ( ) Q P (elastic) Ep>1 %Q>%P (unitary elastic) Ep=1 1:1 Q=%P (inelastic) Ep 0 (Normal Goods) (Y) (Q)0 D 2,000 1,000 10 15 A B Ei 1,000-2,000 = +0.6
  21. 35. (Ei) Ei < 0 (Inferior Goods) (Y) (Q)0 D Slope (-), Ey < 0 1,000 2,000 20 30 B A Ei 1,000-2,000 = -0.6
  22. 36. Ex 2 60,000 A 90,000 64,000 A 100,000 Ei
  23. 37. Ei Ei Ei>0 Normal goods / income inelastic 01 %Q > %Y Ei Ei 0) 2. (Ec < 0) Pb Qa0 Pb 0 D D 1 a b 2 a b Qa Ec > 0 Ec < 0
  24. 44. (Ec) 1. LPG 10 15 LPG 50 70 Ec LPG 10-15 LPG 0 D Slope (+), Ec > 0 10 15 M N 50 70 Ec LPG 10-15 = 0.83 (Ec >0)
  25. 45. (Ec) 2. 10 15 80 60 Ec 10-15 0 D Slope (-),Ei < 0 60 80 10 15 M N Ec 10-15 = -0.71 (Ec