Indifference curves show combinations of goods that provide the same level of satisfaction to a consumer. A consumer seeks to maximize utility by consuming the combination on their highest attainable indifference curve, which is tangent to their budget constraint. As more of a good is consumed, the marginal rate of substitution diminishes, following the law of diminishing marginal rate of substitution. When prices or income change, the budget constraint shifts, changing the optimal consumption bundle where the indifference curve is tangent to the new budget line.

1. INDIFFERENCE CURVES AND UTILITY MAXIMIZATION Indifference curve – A curve that shows combinations of goods which gives the same level of satisfaction to the consumers so that an individual is indifferent.

2. Constructing an indifference curve a Pears Oranges Pears 30 24 20 14 10 8 6 Oranges 6 7 8 10 13 15 20 Point a b c d e f g

3. Assumption More of a commodity is better than less Preference of a consumer are transitive Diminishing marginal rate of substitution

4. More of a commodity is better than less

5. Preference of a consumer are transitive

7. Marginal rate of substitution Marginal rate of substitution – The rate at which consumer is prepared to exchange goods X and Y is known as MRS ie the rate at which one good must be added when the other is taken away in order to keep the individual indifferent between the two combinations without changing total satisfaction .

8. Deriving the marginal rate of substitution ( MRS ) a b Units of good Y Units of good X 26 6 7

9. Deriving the marginal rate of substitution ( MRS ) a b Units of good Y Units of good X 26 6 7  Y = 4  X = 1 MRS = 4

10. Deriving the marginal rate of substitution ( MRS ) a b Units of good Y Units of good X 26 6 7 c d  Y = 4  X = 1  Y = 1  X = 1 MRS = 1 MRS = 4 13 14 9

11. Indifference schedule Indifference schedule Combination Good X Good Y MRS A 1 12 B 2 8 4 C 3 5 3 D 4 3 2 E 5 2 1

12. Marginal Rate of Substitution MRS declines as we move downward to the right along an indifference curve. Indifference curves with diminishing MRS are thus convex. Convexity illustrates that people like variety.

13. Law of diminishing marginal rate of substitution Law of diminishing marginal rate of substitution – As you get more and more of a good X , one is prepared to forego less and less of Y, that is MRS of X for Y diminishes as more and more of good X is substituted for good Y.

14. DMRS

15. An indifference map Units of good Y Units of good X I 1 I 2 I 3 I 4 I 5

16. Properties of Indifference Curve Indifference curves are downward sloping to the right Indifference curves are convex to the origin Indifference curves cannot intersect each other A higher Indifference curves represents a higher satisfaction

17. BUDGET LINE Budget line graphically shows the budget constraint. The combination of commodities lying to the right of the budget line are unattainable because the income of the consumer is not sufficient to be able to buy those combinations. The combination of commodities lying to the left of the budget line are attainable because the income of the consumer is sufficient to be able to buy those combinations

18. What is a Budget Constraint? A budget constraint shows the consumer’s purchase opportunities as every combination of two goods that can be bought at given prices using a given amount of income. The budget constraint measures the combinations of purchases that a person can afford to make with a given amount of monetary income.

19. A budget line Units of good Y Units of good X a b Units of good X 0 5 10 15 Units of good Y 30 20 10 0 Point on budget line a b Assumptions P X = £2 P Y = £1 Budget = £30

20. Effect of an increase in income on the budget line Units of good Y Units of good X Assumptions P X = £2 P Y = £1 Budget = £40 16 7 m n Budget = £40 Budget = £30

21. Effect on the budget line of a fall in the price of good X Units of good Y Units of good X Assumptions P X = £1 P Y = £1 Budget = £30 B 1 B 2 a b c

22. The Best Feasible Bundle Tools needed to determine how consumers should allocate their income between 2 goods : Budget Constraint Indifference Curves Consumer’s strategy is to keep moving to higher and higher indifference curves until he reaches the highest one that is still affordable.

23. How to Find the Best Combination Utility is maximized when: the indifference curve is just tangent to the budget line.

24. Consumer Equilibrium

25. The Best Affordable Bundle

26. Finding the optimum consumption I 1 I 2 I 3 I 4 I 5 Units of good Y O Units of good X Budget line

27. indifference curve and budget line I 1 I 2 I 3 I 4 I 5 Units of good Y O Units of good X r s t Y 1 X 1 v u

28. Units of good Y O Units of good X B 1 Effect on consumption of a change in income I 1

29. I 2 Units of good Y O Units of good X B 1 B 2 I 1 Effect on consumption of a change in income

30. I 2 Units of good Y O Units of good X B 1 B 2 B 3 B 4 I 1 I 3 I 4 Effect on consumption of a change in income

31. I 2 Units of good Y O Units of good X B 1 B 2 B 3 B 4 I 1 I 3 I 4 Income–consumption curve Effect on consumption of a change in income

32. Utility Maximization