ECON-221 Lecture Notes - Lecture 6: Robert Giffen, Ceteris Paribus, Demand Curve

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azureprairie-dog22

20 Aug 2020

School

Diablo Valley College

Department

Economics

Course

ECON-221

Professor

yoon

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Document Summary

An individual"s demand for a good, says good x, is the quantity of the good (good x) that the individual is willing and able to buy during some time period. Suppose we list some of the factors, which may be expected to influence this consumer"s demand for good x over a given period (dx) as below: Using functional notation, we write the following demand function: dx = f(px, ps, y, t, e, a, z). This states simply that the individual"s demand for quantity demanded of x is a function of all the factors listed in the brackets. However, economists analyze the relationship between a consumer"s demand for x and the price of x by assuming that all the other factors influencing demand remain unchanged. This is the important ceteris paribus assumption which is used so widely in all branches of economics . we can now write the factions: dx = f(px), "ceteris paribus. "

Related Questions

Suppose that the extended (generalized) demand function for good Y is:

Q_d^Y= 250,000 - 500 P_Y -1.5 M + 240 P_X

where: Q_d^Y = quantity demanded of good Y

P_Y = Price of good Y

M = Average income of consumers

P_X = Price of related good X

a) If M = $ 60,000 and P_X = $100, what is the reduced demand function for good Y?

b) Continue using the reduced demand equation from part a,

If M = $60,000, P_X = $100, and P_Y = $200 then Q_d^Y = ________

If M = $60,000, P_X = $100, and P_Y = $300 then Q_d^Y = ________

Use this information (prices and quantities demanded of good Y) to calculate the price elasticity of demand between these two points on the demand curve of good Y. Show your work.

c) Use your answer to part b. Between these two points on the demand for good Y, is demand elastic, inelastic, or unitary price elastic? Why? What will happen to total revenues if the price increases between these two points on the demand curve?

d) In part b, you found that when:

M = $60,000, P_X = $100, and P_Y = $200 then Q_d^Y = ________

Now let's suppose that the price of the related good X decreases from $100 to $50 but income remains constant (at $60,000). Assume that the price of good Y is also constant at $200.

If M = $60,000, P_X = $50, and P_Y = $200 then Q_d^Y = ________

Use these prices of good X and the quantities demanded of good Y to calculate the cross-price elasticity of the demand for good Y when the price of good X decreases from $100 to $50.

e) Consider your answer to part d. Based on the value of the cross-price elasticity of demand you just estimated, are goods X and Y substitutes, complements, or unrelated? Why?

f) In part b, you found that when:

M = $60,000, P_X = $100, and P_Y = $200 then Q_d^Y = ________

Now let's suppose that consumer income increases from $60,000 to $80,000 but the price of good X remains constant (at $100). Assume that the price of good Y is also constant at $200.

If M = 80,000 , P_X = $100 and P_Y = $200 then Q_d^Y = _________

Use these income levels and quantities demanded of good Y to calculate the income elasticity of the demand for good Y when income increases from $60,000 to $80,000.

Show your work

g) Consider your answer to part f. Based on the value of the income elasticity of demand you just estimated, is good Y normal, inferior, or income independent?

erinalligator549

PROBLEM 1 (This one is designed to give you lots of math practice!)

Consider the following individual utility functions:

Adam Smith: U(x,y) = xy

Jeremy Bentham: U(x,y) = x^ay^b (Cobb-Douglas utility function)

Alfred Marshall: U(x,y) = ln x + ln y

John M. Keynes: U(x,y) = x + y^b (Quasi-linear utility function)

Joan Robinson: U(x,y) = aX + bY (linear; perfect substitutes)

a. Solve for the MRS(XY) for each of the gentlemen (i.e., all but Joan Robinson). Show that Mr. Smith, Mr. Bentham, and Mr. Marshall all have diminishing MRS(XY), but that if a=b=2, their preferences exhibit constant, increasing, and decreasing marginal utility respectively. (Fortunately, diminishing MRS is the condition that guarantees convex indifference curves, so we can solve for their optimal consumption!)

b. What is the general formula for Mrs. Robinsons (constant) MRS?

c. Find demand functions for x and y for Smith, Bentham, Marshall, and Keynes. Assume that each man has income I and that the prices of x and y are p_x and p_y respectively.

d. Now assume that a=1/2, b = 1/4, I = 600, p_x = 10 and p_y = 20. Use these values to find the utility-maximizing quantities of x and y consumed by each man.

e. Find an expression for the share of income Mr. Bentham and Mr. Marshall each devote to the consumption of good x, where this share, s_x, is defined as

(p_x x)/I.

f. Find expressions for the income elasticity of demand for good x for Mr. Bentham and Mr. Marshall. Find expressions for the (own) price elasticity of demand for good y for these two men.

aquamarinescorpion997

Question 1

The law of demand states that there is a direct relationship between supply and demand.

True

False

4 points

Question 2

Equilibrium is a state of balance between supply and demand.

True

False

4 points

Question 3

Goods are scarce for both rich and poor.

True

False

4 points

Question 4

"The big corporations in this country, like ExxonMobil and GM, have deep pockets and need to be hiring more people." This is a positive statement about economic policy.

True

False

4 points

Question 5

The law of supply states that there is a direct relationship between price and quantity demanded.

True

False

4 points

Question 6

In the circular flow model, firms own economic resources, and householdsbuy the manufactured products and services.

True

False

4 points

Question 7

Households play a dual role of providing the factors of production whilepurchasing the goods and services of firms.

True

False

4 points

Question 8

Opportunity cost is the lowest valued benefit that must be sacrificed asthe result of choosing an alternative.

True

False

4 points

Question 9

Scarcity denotes that our desire for a good exceeds the amount that isfreely available from nature.

True

False

4 points

Question 10

Economics is a social science concerned with satisfying man's unlimitedwants with limited resources.

True

False

4 points

Question 11

Joint output of individuals or nations will be maximized when goods areexchanged between parties in accordance with the law of"comparative advantage".

True

False

4 points

Question 12

The production possibilities frontier assumes that the level of technologyvaries when applying the model.

True

False

4 points

Question 13

Excess demand in the market will cause the price of a product to decline.

True

False

4 points

Question 14

Demand is measured on the vertical axis and supply on the horizontalaxis.

True

False

4 points

Question 15

A change in quantity demanded is a movement along the same demandcurve.

True

False

4 points

Question 16

As globalization and world trade proliferates, individual markets withincountries' economies become more competitive.

True

False

4 points

Question 17

Which growth theory compares a subsistence real wage rate to the actual real wage rate?

		Classical growth theory
		Inflation growth theory
		Neoclassical growth theory
		New growth theory

4 points

Question 18

Suppose the working age population in Tiny Town is 100 people. If 25 of these people are NOT in the labor force, the ________ equals ________.

		unemployment rate; 25/100 Ã 100
		employment rate; 25/75 Ã 100
		labor force; 75
		labor force; 25/100 Ã 100

4 points

Question 19

Suppose there is a rise in the real wage rate. As a result, the quantity of labor demanded:

		increases.
		decreases.
		does not change because there is no change in the money wage rate.
		increases only if the price level also decreases.

4 points

Question 20

GDP can be computed as the sum of:

		all sales that have taken place in an economy over a period of time.
		the total expenditures of consumers and business over a period of time.
		the total expenditures of consumption, investment, and government expenditure on goods and services over a period of time.
		the total expenditures of consumption, investment, government expenditure on goods and services, and net exports over a period of time.

4 points

Question 21

The real wage rate equals:

		(100 x (money wage rate/price level)
		(100 x (price level/money wage rate)
		(money wage rate x (price level)
		(money wage + (number of hours worked/(price level)

4 points

Question 22

If the CPI was 121.5 at the end of 2007 and 138.3 at the end of 2008, the inflation rate over these two years was:

		10.2 percent.
		13.8 percent.
		12.2 percent.
		16.8 percent.

4 points

Question 23

A movement along the production function is the result of a change in:

		the quantity of labor.
		technology.
		capital.
		interest rates.

4 points

Question 24

All of the following are part of fiscal policy EXCEPT:

		setting tax rates.
		setting government spending.
		choosing the size of the government deficit.
		controlling the money supply.

4 points

Question 25

Along a production possibilities frontier for real GDP and the quantity of leisure time, as leisure time increases, real GDP:

		decreases.
		increases.
		stays the same.
		could increase, decrease or stay the same.

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ECON-221 Lecture Notes - Lecture 6: Robert Giffen, Ceteris Paribus, Demand Curve

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