MANAGERIAL ECONOMICS IN A GLOBAL

DOMINICK SALVATORE

THE BASIC OF DEMAND, SUPPLY THE BASIC OF DEMAND, SUPPLY AND EQUILIBRIUMAND EQUILIBRIUM

Lecture for MM CORDEV -11 (PJJ) Bandung, 2 -9- 13

By : Teguh Widodo

tewidodo@gmail.comTwitter : broTeguh

02135126126

Scope

• Demand side of market– Demand theory and curve– Effect of non-price to demand

• Supply side of market– Supply teory and curve– Effect of non-price to supply

• Equilibrium & Change of equilibrium• Elasticity

Management Decision ProblemManagement Decision Problem

Decesion Science:Math. Economics

Econometrics

Decesion Science:Math. Economics

Econometrics

Economic Theory:Microeconomics, Macroeconomics

Economic Theory:Microeconomics, Macroeconomics

MANAGERIAL ECONOMICSAplication of economic theory and

decision science tools to solve managerial decision problems

MANAGERIAL ECONOMICSAplication of economic theory and

decision science tools to solve managerial decision problems

OPTIMAL SOLUTION TO MANAGERIAL DECISION PROBLEM

OPTIMAL SOLUTION TO MANAGERIAL DECISION PROBLEM

The Nature of Managerial Economics

Economics begins and ends with the “Law” of supply and demand. The laws of supply and demand are an important beginning in the attempt to answer vital questions about the working of a market system.

Demand for a good or service is defined as quantities of a good or service that people are ready (willing and able) to buy at various prices within some given time period, other factors besides price held constant.

The supply of a good or service is defined as quantities of a good or service that people are ready to sell at various prices within some given time period, other factors besides price held constant.

DEMAND AND SUPPLY

Demand Side

• Every market has a demand side and a supply side.• The demand side can be represented by a market

demand curve which shows the amount of commodity buyers would like to purchase at different prices.

• Demand curves are drawn on the assumption that buyers’ tastes, income, the number of consumers in the market and the price of related commodities are unchanged.

LAW OF DEMAND

The inverse relationship between the price of the commodity and the quantity demanded per period is referred to as the law of demand.

A decrease in the price of a good, all other things held constant (ceteris paribus), will cause an increase in the quantity demanded of the good.

An increase in the price of a good, all other things held constant, will cause a decrease in the quantity demanded of the good.

Change in Quantity Demanded

Quantity

Price

P0

Q0

P1

Q1

An increase in price causes a decrease in quantity demanded.

Change in Quantity Demanded

Quantity

Price

P0

Q0

P1

Q1

A decrease in price causes an increase in quantity demanded.

Changes in Demand

• Changes in price result in changes in the quantity demanded.– This is shown as movement along the

demand curve.

• Changes in nonprice determinants result in changes in demand.– This is shown as a shift in the demand

curve.

Changes in Demand

• Change in Buyers’ TastesToday’ consumer purchases leaner meats compared to old generations due to the level of blood cholesterol and body weight

• Change in Buyers’ Incomes– Normal Goods : i.e., shoes, steaks, travel, automobiles,

education – Inferior Goods: i.e., potatoes, hotdogs, hamburger

• Change in the Number of Buyers• Change in the Price of Related Goods

– Substitute Goods : i.e., Carrots can be replaced by cabbage

– Complementary Goods : i.e., cars and gasoline or electric stove and electricity.

Change in Demand

Quantity

Price

P0

Q0 Q1

An increase in demand refers to a rightward shift in the market demand curve.

Change in Demand

Quantity

Price

P0

Q1 Q0

A decrease in demand refers to a leftward shift in the market demand curve.

Demand, Supply and Equilibrium

• Every market has a demand side and a supply side. The Supply side can be represented by a market supply curve which shows the amount of commodity sellers would offer a sale at various prices.

• Supply curves are drawn on the assumption of technology and input or resources (as such labor, capital and land) and prices.

Law of Supply

• The direct relationship between the price of the commodity and the quantity supplied per period is referred to as the law of supply.

• A decrease in the price of a good, all other things held constant (ceteris paribus), will cause a decrease in the quantity supplied of the good.

• An increase in the price of a good, all other things held constant, will cause an increase in the quantity supplied of the good.

Change in Quantity Supplied

Quantity

Price

P1

Q1

P0

Q0

A decrease in price causes a decrease in quantity supplied.

Change in Quantity Supplied

Quantity

Price

P0

Q0

P1

Q1

An increase in price causes an increase in quantity supplied.

Changes in Supply

• Nonprice determinants of supply– Costs and technology– Prices of other goods or services offered by

the seller– Future expectations– Number of sellers– Weather conditions

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Changes in Supply

• Change in Production Technology- An improvement in the technology and a reduction in input prices would make it possible to produce a commodity at a lower cost. This indicates that sellers would be willing to sell more the goods at each price

• Change in Input Prices-↓ in agriculture product, ↓ price of lamb meat, ↑ quantity supplied so rightward shift in the market supply curve

• Change in the Number of Sellers- ↑ in no of sellers, the market supply curve shifts to right or ↓ in no of sellers, the market supply curve shifts to left

• Prices of other goods or services offered by the seller- i.e., BMW, Mercedes, Woswagen (Subs. Goods)- i.e., lamp meat and lamp leather (comp. Goods)

Change in Supply

Quantity

Price

P0

Q1Q0

An increase in supply refers to a rightward shift in the market supply curve.

Change in Supply

Quantity

Price

P0

Q1 Q0

A decrease in supply refers to a leftward shift in the market supply curve.

Market Equilibrium

• Market equilibrium is determined at the intersection of the market demand curve and the market supply curve.

• Equilibrium price: The price that equates the quantity demanded with the quantity supplied.

• Equilibrium quantity: The amount that people are willing to buy and sellers are willing to offer at the equilibrium price level.

• The equilibrium price causes quantity demanded to be equal to quantity supplied.

• An increase or decrease in the demand or supply curve, it defines a new equilibrium point.

Market Equilibrium

Price

P

Q

D S

If the quantity supplied of a commodity exceeds the quantity demanded, this is called excess supply or surplus between D and S over point p.

If the quantity demanded of a commodity exceeds the quantity supplied, this is called excess demand or shortage between D and S below point p.

Market Equilibrium

• Shortage: A market situation in which the quantity demanded exceeds the quantity supplied.– A shortage occurs at a price below the

equilibrium level.• Surplus: A market situation in which the

quantity supplied exceeds the quantity demanded.– A surplus occurs at a price above the

equilibrium level.

Market Equilibrium

Market Equilibrium

Quantity

Price

P0

Q0

D0 S0

Q1

P1

D1

An increase in demand will cause the market equilibrium price and quantity to increase.

Market Equilibrium

Quantity

Price

P1

Q1

S0

Q0

P0

D0D1

A decrease in demand will cause the market equilibrium price and quantity to decrease.

Market Equilibrium

Quantity

Price

P0

Q0

D0 S0

Q1

P1

An increase in supply will cause the market equilibrium price to decrease and quantity to increase.

S1

Market Equilibrium

Quantity

Price

P1

Q1

D0

Q0

P0

A decrease in supply will cause the market equilibrium price to increase and quantity to decrease.

S1 S0

The Demand Schedule and the demand curve-Example

How can the relationship between quantity demanded and price be portrayed?

Demand schedule

Demand curve

DBadu

D

PERMINTAAN

Ceteris Paribus

P1

P2

Q2

Efek harga thd permintaan

The Equilibrium Price at 4$

E

Ceteris Paribus

Excess Demand

Excess Supply

D1 D0 D2

• HARGA BARANG LAIN– Barang pengganti (kopi – teh)– Barang pelengkap (gula – kopi/teh)– Barang netral (beras – buku tulis)

• PENDAPATAN PARA PEMBELI– Barang inferior (gaplek): negatif– Barang esensial (sembako): netral– Barang normal (pakaian): positif– Barang mewah (mobil): positif

• FAKTOR LAIN– Distribusi pendapatan– Citra rasa masyarakat– Jumlah penduduk– Ekspektasi masa depan

• KENAIKAN HARGA BARANG LAIN • BIAYA FAKTOR PRODUKSI --• TUJUAN OPERASI PERUSAHAAN --

• Profit optimation.• Profit maximation.

• TINGKAT TEKNOLOGI YG DIGUNAKAN --• Increasing production• Cost efficiency increasing profit.

The Equilibrium Shifting

E0

Individual Demand function

The demand for a commodity arises from the consumers’ willingness and ability to purchase the commodity. Consumer demand theory postulates that the quantity demanded of a commodity is a function of / or depends on the price of the commodity, the consumers’ income, the price of related commodities, and the tastes of the consumer.

Individual Consumer’s DemandQdX = f(PX, I, PY, T)

quantity demanded of commodity X by an individual per time period

price per unit of commodity X

consumer’s income

price of related (substitute or complementary) commodity

tastes of the consumer

QdX =

PX =

I =

PY =

T =

Functional form

Qdx= (Px, I, Py, T)

An inverse relationship is expected between the quantity demanded of a commodity and its price (law of demand). That is, when the price rises, the quantity purchased declines, and when the price falls, the quantity sold increases.

QdX = f(PX, I, PY, T)

QdX/PX < 0 if a good is superior

QdX/I > 0 if a good is normal

QdX/I < 0 if a good is inferior

QdX/PY > 0 if X and Y are substitutes

QdX/PY < 0 if X and Y are complements

HORIZONTAL SUMMATION: FROM INDIVIDUAL TO MARKET DEMAND

Market Demand FunctionQDX = f(PX, N, I, PY, T)

quantity demanded of commodity X

price per unit of commodity X

number of consumers on the market

consumer income

price of related (substitute or complementary) commodity

consumer tastes

QDX =

PX =

N =

I =

PY =

T =

DEMAND FACED BY A FIRM Market Structure

Monopoly Oligopoly Monopolistic Competition Perfect Competition

Type of Good Durable Goods Nondurable Goods Producers’ Goods - Derived Demand

LINEAR DEMAND FUNCTION

QX = a0 + a1PX + a2N + a3I + a4PY + a5T

PX

QX

Intercept:a0 + a2N + a3I + a4PY + a5T

Slope:QX/PX = a1

ELASTICITY OF DEMANDELASTICITY OF DEMAND

PRICE ELASTICITY OF DEMANDPRICE ELASTICITY OF DEMAND

The price elasticity of demand (Ep) is mainly depends on the following factors: Existence of substitutes effect

e.g. Oil product cannot easily be substituted-demand of oil product is inelastic.

e.g. The demand for taxi services is expected to be elastic. Instead, You may use bus, train etc..

The price elasticity of demand (Ep) is mainly depends on the following factors: The portion of money allocated in the

budgeto A change in the price of a product do not

influence consumers’ budget in a negative way.

e.g. An increase in black pepper will not decrease the demand of consumers on black pepper due to their small portion of money allocated in their budget.

The price elasticity of demand (Ep) is mainly depends on the following factors: The time period after changes in price

o As long as time period gets longer, the demand becomes more elastic.

e.g. When oil prices increase, consumers cannot find a solution to change the current system to another alternative system in a short run period. This shows us demand for oil will remain same to a certain extent and an increase or a decrease in demand will be depend on time.

Price Elasticity of Demand

The price elasticity of demand (Ep) is measured by the percentage change in the quantity demanded of the commodity divided by the percentage change in commodity’s price, holding constant all other variables in the demand function.

/

/P

Q Q Q PE

P P P Q

PRICE ELASTICITY OF DEMAND

/

/P

Q Q Q PE

P P P Q

Point Definition

Arc Definition 2 1 2 1

2 1 2 1P

Q Q P PE

P P Q Q

Calculus approach

Market

AB

CD

EF G

0

2

4

6

8

0 200 400 600 800 1000 1200

Qdx

PxQ = 600-100P

Point P ($) Q (unit)

A 6 0B 5 100C 4 200D 3 300E 2 400F 1 500G 0 600

Point Elasticity of Demand- Example

Arc Elasticity of Demand- Example

Find arc Ep between points B and C Ep=(Q2-Q1)/(P2-P1)*(P2+P1)(Q2+Q1) Ep= (400-200)/(4-5) (4+5)/(400+200) Ep=-3

Absolute value of Ep Greater than 1- elastic Equals 1- unit elastic Less than 1- inelastic

PRICE ELASTICITY, TOTAL REVENUE AND MARGINAL REVENU

Point P ($)Q

(unit)

Ep =∆Q/∆P *

P/Q

TR=P*Q

MR = ∆TR/∆Q

A 6 0 -∞ 0 -B 5 100 -5 500 5C 4 200 -2 800 3D 3 300 -1 900 1E 2 400 -0,5 800 -1F 1 500 -0,2 500 -3G 0 600 0 0 -5

Fungsi permintaan Q = 600 – 100 P. Hitung elastisitas permintaan bila jml yg diminta .

a.Q = 100b.Q = 300c.Q = 500

a.Q = 600 – 100P dQ/dP = -100

P = 6 - Q/100 Q = 100 P = 6-1 = 5

Ep = dQ/dP * P/Q = -100* 5/100 = - 5

b. Q = 600 – 100P dQ/dP = -100

P = 6 - Q/100 Q = 300 P = 6-3 =3

Ep = dQ/dP * P/Q = -100* 3/300 = - 1

Calculus Solution

Calculus approach:

Find MR by using P and Ep at Px =$4 and $3 MR= P{1+(1/Ep)}

At Px =$4 MR=4{1+(1/-2)=$2 At Px =$3 MR=3{1+(1/-1)=0

Based on the previous table: P decreases TR increases when Ep is elastic TR max or unchanged when Ep is unitary

elastic TR decreases when Ep is inelastic

TR

DEp = (dQ/dP)(P/Q) = -100.3/300= -1Jika permintaan elastis thd harga (0-300 unit) maka penurunan harga menaikan TR. TR maks pd unitary price, yi Q =300.Jika demand tidak elastis (yi Q>300), maka setiap penurunan harga menurunkan TR, dan MR negatif.

Demand, TR, MR and Price Elasticity

LATIHAN ELASTISITAS

1. Fungsi permintaan P = 150 -2Q. Hitung elastisitas permintaan bila jml yg diminta .a. Q = 35b. Q = 37,5c. Q = 50

2. Fungsi permintaan P = 150 – 1/3 Q. Hitung elastisitas permintaan bila harganya :.a. P = 5b. P = 45

3. Bila tingkat harga $ 2 , jml yg diminta 8 unit, bila $4 yg diminta 6 unit. Dg menganggap fungsi permintaan adalah linear, berapa elastisitas permintaan pada harga 1. $3,-2. $4,-

4. Pada fungsi permintaan Q = 20 – 2 P^2, hitung elastisitas permintaan pada harga $ 2,- per unit.

MARGINAL REVENUE AND PRICE ELASTICITY OF DEMAND

11

P

MR PE

MARGINAL REVENUE AND PRICE ELASTICITY OF DEMAND

PX

QX

MRX

1PE

1PE

1PE

MARGINAL REVENUE, TOTAL REVENUE, AND PRICE ELASTICITY

TR

QX

1PE MR<0MR>0

1PE

1PE MR=0

DETERMINANTS OF PRICE ELASTICITY OF DEMAND

Demand for a commodity will be more elastic if:

It has many close substitutes It is narrowly defined More time is available to adjust to a price

change

DETERMINANTS OF PRICE ELASTICITY OF DEMAND

Demand for a commodity will be less elastic if: It has few substitutes It is broadly defined Less time is available to adjust to a price

change

INCOME ELASTICITY OF DEMAND

Point Definition: /

/I

Q Q Q IE

I I I Q

Calculus approach:

Arc Definition: 2 1 2 1

2 1 2 1I

Q Q I IE

I I Q Q

Normal Good Inferior Good

0IE 0IE

CROSS-PRICE ELASTICITY OF DEMAND

Linear Function

Point Definition/

/X X X Y

XYY Y Y X

Q Q Q PE

P P P Q

4Y

XYX

PE a

Q

CROSS-PRICE ELASTICITY OF DEMAND

Arc Definition

Substitutes Complements

2 1 2 1

2 1 2 1

X X Y YXY

Y Y X X

Q Q P PE

P P Q Q

0XYE 0XYE

Calculus approach:

Exy = dQ/dPy * Py /Qy

OTHER FACTORS RELATED TO DEMAND THEORY

International Convergence of Tastes Globalization of Markets Influence of International Preferences on Market

Demand Growth of Electronic Commerce

Cost of Sales Supply Chains and Logistics Customer Relationship Management

1. Di Kota Bandung terdapat tiga perguruan tinggi (PT) yang membutuhkan buku dari agen tunggal PT Globook. Respons dari masing2 PT terhadap harga berbeda-beda dengan data sbb:

Harga (IDR) Buku yg diminta Buku yg dijual

PT X PT Y PT Z PT Globook

50000 100 100 150 2000

40000 150 150 200 1400

30000 300 200 300 800

20000 500 300 400 200

10000 700 450 500 0

Denganpasar diasumsikan ceteris paribus,

1. Gambarkan kura permintaan dan penawaran pasar. 2. Hitung harga ekuilibrium pasar. 3. Apa yang terjadi jika PT Globook mematok harga jual Rp 40.000,00; bagaimana pula

jika penjual mengobral buku dg harga Rp 30.000,00? 4. Hitung elastisitas busur pada setiap terjadi perubahan harga dari Rp 50.000,00 ke Rp

40.000,00 ke Rp 30.000,00 dan ke 20.000,00.

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INCOME ELASTICITY OF DEMAND

/

/I

Q Q Q IE

I I I Q

Point Definition

Linear Function

3I

IE a

Q

70

INCOME ELASTICITY OF DEMAND

2 1 2 1

2 1 2 1I

Q Q I IE

I I Q Q

Arc Definition

Normal Good Inferior Good

0IE

Luxuries GoodNecessities Good

0IE

1IE 1I0 < E <

71

CROSS-PRICE ELASTICITY OF DEMAND

/

/X X X Y

XYY Y Y X

Q Q Q PE

P P P Q

Point Definition

Linear Function 4Y

XYX

PE a

Q

72

CROSS-PRICE ELASTICITY OF DEMAND

2 1 2 1

2 1 2 1

X X Y YXY

Y Y X X

Q Q P PE

P P Q Q

0XYE

Arc Definition

Substitutes Complements

0XYE

XYE No relationship

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INCOME, CROSS AND ARC ELASTICISES- EXAMPLE

Find arc EI between two levels of income i.e I=$10000 and I=$ 11000 when the demand for commodity X is 400.Ep={(Q2-Q1)/(I2-I1)}*{(I2+I1)/(Q2+Q1)}Ep= {(600-400)/(11-10)}*{(11+10)/(600+400)}EI= 4.2

Thus commodity X is normal and luxury.

Find arc Exy between two levels of price Y i.e Py=$ 1 and Py =$ 2 when the demand for commodity X is 400.Ep={(Q2-Q1)/(P2-P1)}*{(P2+P1/)/(Q2+Q1)}Ep= {(600-400)/(2-1)}*{(2+1)/(600+400)}EI= 0.6

Thus commodity Y is substitute compared to commodity X

Market

AB

CD

EF G

0

2

4

6

8

0 200 400 600 800 1000 1200

Qdx

Px

0XYE Substitutes

74

USING ELASTICISES IN MANAGERIAL DECISION MAKING-EXAMPLE

A firm selling coffee brand X and estimated relevant demand regression as follows:

Qx=1.5 - 3Px + 0.8I + 2Py - 0.6Ps + 1.2AQx is sales of coffee brand X, I is disposable income, Py is price of competitive coffee brand,

Ps is price of sugar and A is advertising expenditures for coffee brand X.Suppose: Px=$2,

I=$2.5,

Py=$1.80,

Ps=$0.50 and

A=$1

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USING ELASTICITIES IN MANAGERIAL DECISION MAKING EXAMPLE

Calculate Qx and the elasticities of sales with respect to each variable in the relevant demand function

Qx=1.5-3.0 Px+0.8 I+2.0 Py-0.6 Ps+1.2 AQx=1.5-3.0(2)+0.8(2.5)+2(1.8)-0.6(0.5) +1.2(1)

=2 million pounds coffee

Calculate the elasticities of the demand for coffee brand X

Ep=-3(2/2)=-3,Ei=0.8(2.5/2)=1, Exy=2(1.8/2) ES= -0.6(0.5/2)=-0.15, EA=1.2(1/2)=0.6

RECALL the Formula

3I

IE a

Q

1P

PE a

Q

4Y

XYX

PE a

Q

76

USING ELASTICISES IN MANAGERIAL DECISION MAKING-EXAMPLE

Next year, the firm would like to increase PX by 5%, A by 12%, I by 4%, and PY 7% whereas Ps fall by 8%.

Determine sales of coffee brand X in the next year.

Qxx = QX+ {QX(∆PX/PX)EP + Qx(∆I/I)EI + Qx(∆Py/Py)Exy + Qx(∆A/A)EA }

Qxx=2+2(5%)(-3)+2(4%)(1)+2(7%)(1.8)+2(-8%)(-0.15)+2(12%)(0.6)

Qxx=2.2 or 2,200,000 pounds

HOW DO YOU İNTERPRET?7

7

78

HOW DO YOU İNTERPRET?

1 percent increase in price leads to a reduction in the quantity demanded of clothing of 0f 0.90 percent in the short-run and 2.90 percent in the long-run.

Price elasticity of demand for gasoline is three times higher in the long-run.

Both elasticities are very small. It seems that people cannot find suitable substitutes

for gasoline.

HOW DO YOU İNTERPRET?7

9

80

HOW DO YOU İNTERPRET?

Income elesticity of demand is 2.59 for wine and -0.36 for flour. This means that a 1 percent increase in consumers’ income leads to a 2.59 percent increase in expenditure on wine but to a 0.36 percent reduction in expenditures on flour.

Thus wine is a luxury while flour is a inferior good. Electricity is also a luxury and so European cars,

Asian cars, and domestic cars in the U.S. While cigarettes, beer, chicken and pork are necessities. Beef is a borderline commodity

HOW DO YOU İNTERPRET?8

1

82

HOW DO YOU İNTERPRET? The cross price elesticity of demand of margarine with

respect to the price of butter is 1.53 percent. This means that a 1 percent increase in the price of butter leads to a 1.53 percent increase in the demand for margarine.

Thus margarine and butter are substitutes in the U.S. The cross price elesticity of demand of cereals (e.g.

Bread) with respect to the price of fresh fish is -0.87 percent. This means that a 1 percent increase in the price of cereals leads to a 0.87 percent reduction in the demand for fresh fish.

Thus cereal and fresh fish are complements.

HOW DO YOU İNTERPRET?

83

84

HOW DO YOU İNTERPRET? The price elesticity of demand of beer is -0.23 percent.

This means that a 10 percent increase in the price of beer leads to a 2.3 percent reduction in the quantity of beer demanded and thus an increase in consumer expenditures on beer.

The price elesticity of wine is -0.40 and spirits is -0.25 so that an increase in their price also leads consumers to demand a smaller quantity of wine and spirits, but also to spend more on the alcoholic beverages.

The cross price elesticity of demand for beer with respect to the price of wine is 0.31 and with respect to spirits is 0.15. This means that wine and spirits are substitutes for beer, with wine being better substitute.

85

HOW DO YOU İNTERPRET?

Thus a 10 percent increase in the price of wine will lead to a 3.1 percent increase in demand for beer, while a 10 percent increase in the price of spirits leads to a 1.5 percent increase in demand for beer.

a 10 percent increase in consumer income will lead to a 0.9 percent reduction in the demand for beer, but 50.3 percent increase in demand for wine, while a 12.1 percent increase in demand for spirits.

Thus beer can be considered an inferior good, while wine and spirits can be regarded as a luxury goods.

Wine seems much stronger luxury than spirits.

86

THE İMPORTANT STEPS BY USİNG ELASTİCİTİES

The analysis of the forces or variables that affect on demand and reliable estimates of their quantitative effect on sales (elasticities) are essential in order for firm to make best operating decisions in shor-run and to plan for its growth in the long-run.

The firms can use the elasticities of demand of the variables under their controls to find out best policies as well as to maximize their profits.

If the demand for the firm’s product is price inelastic, the firm will want to increase the product price since that would increase its total revenue and reduce its total cost.

If the elasticity of the firm’s sales wrt the variable beyod its control or If the cross-price elasticity of demand for the firm’s product is very high, the firm will need to respond quickly to a competitor’s price reduction otherwise losing a great deal of its sales.

87

THE İMPORTANT STEPS BY USİNG ELASTİCİTİES

The size of the price elasticity of demand is larger, the closer and the greater is the number of available substitutes for the commodity. For example, sugar is more price elastic than table salt (e.g. honey)

In general, the greater is its price elasticity of demand, the greater will be the number of substitutes

For a given price change, the quantity response is likely to be much larger in the long run than short run so the price elasticity of demand is likely to be much greater in the long run than short run .

1. Permintaan mobil Chevrolet di US dimodelkan sbb:

Qc = 100000 – 100Pc + 2000N + 50I + 30Pf – 1000Pg + 3A + 40000Pi

Dimana

Qc = quantity demanded per year of Chevrolet automobiles

Pc = price of Chevrolet automobile

N = population of US, in millions

I = per capita dispossible income

Pf = price of Ford automobiles, in dollars

Pg = real price of gasoline, in cents per gallon

A = advertizing expenditure by Chevrolet, in dollars per year

Pi = credit incentives to purchase Chevrolets, in percentage points below the rate of interest on borrowing in the absence of incentive.

1. Tunjukan perubahan pembelian Chevrolets tiap tahun untuk setiap unit perubahan

pada variabel bebas . 2. Turunkan kurva permintaan jika diketahui harga Chevrolet rata-rata $9.000, jumlah

penduduk 200 juta, pendapatan per kapita $ 10.000,00, harga mobil Ford $8.000,00, harga bensin $8 sen per galon, biaya iklan $ 50.000,00 per triwulan dan Chevrolet memberikan insentif kredit $ 1,00. Berapa jumlah Chevrolet yg diminta?

3. Buat analisis seandainya harga Chevrolet naik 10% dan harga mobil Ford naik 10% dan harga bensin naik 25% dan pendapatan per kapita naik 5% sedangkan lainnya tetap.

Interpretation of elasticities

Midwest Cable TV has estimated the demand for its service to be given by the following function:

Q = 9,83 P -1,2 A2.5 Y 1,6 P0 1,4

whereQ = monthly sales in unitsP = price of the service in $A = promotional expenditure in $’000Y = average income of the market in $’000P0 = price of ‘home movies’ in $

The current price of Midwest is $60, promotional expenditure is$120,000, average income is $28,000, and the price of ‘homemovies’ is $45.

Indicate whether the following statements are true or false, givingyour reasons and making the necessary corrections.

a. If Midwest increases its price this will reduce the number of its customers.b. If Midwest increases its price this will reduce its revenues.c. People’s expenditure on the cable TV service as a proportion of their income will increase when their income increases.d. If Midwest increases its price this will increase the sales of ‘home movies’.e. ‘Home movies’ are a substitute for cable TV.f. A 5 per cent increase in income will increase demand by 16 per cent.g. A 10 per cent increase in price will reduce demand by 12 per cent.h. Current sales are over a million units a month.i. The demand curve for Midwest is given by: Q=9,83P1,2

j. Midwest’s sales are more affected by the price of ‘home movies’ than by the price of its own service.k. If Midwest increases its price this will reduce its profit.

1. True; customers and quantity demanded are synonymous in this case, and there is an inverse relationship between Q and P, as seen by the negative price elasticity.

2. True; demand is elastic, since the PED is greater than 1 in absolute magnitude. Therefore an increase in price causes a greater than proportional decrease in quantity demanded and a fall in revenue.

3. True; this is because the YED is greater than 1, indicating that cable TV is a luxury product. Note that the statement would be false if the good were a staple. For staples, although expenditure on the roduct increases as income increases, expenditure as a proportion of income falls, since expenditure rises more slowly than income.

4. False; the two products are complementary, shown by the CED being negative; therefore an increase in the price of one product will reduce the sales of the other. It appears therefore that ‘home movies’ is a cable channel.

5. False; the two products are complementary, shown by the CED being negative.

7. False; YED = 1,6; therefore using the simple elasticity formula (reasonably accurate for small changes) the change in demand will be 1,6 * 5% = 8%.

8. False; change is 1,2 * 10% = 12%, but this is a change in quantity demanded, corresponding to a movement along a demand curve (unlike the previous part of the question, which involves a shift in the demand curve).

9. False; current sales are given by Q=9.83(60)1,2 (120)2,5 (28)1,6 (45)1,4 = 11.420 units.

10. False; the demand curve is given by Q = 9,83P1,2 1202,5 281,6 451,4 . Or Q = 1.554.039P1,2.

11. True; the CED is larger in absolute magnitude than the PED. This is an unusual situation but arises because of the nature of cable TV service. The service is only a means to an end, that of receiving certain channels.

12. False; since demand is elastic, an increase in price has an unknown effect on profit. More information would be required.

Marginal effects and elasticity PK Corp estimates that its demand function is as follows:

Q = 150 + 5,4P + 0,8A + 2,8Y + 1,2P*

whereQ = quantity demanded per month (in 1000s)P = price of the product (in £)A = firm’s advertising expenditure (in £’000 per month)Y = per capita disposable income (in £’000)P = price of BJ Corp (in £).

a. During the next five years, per capita disposable income is expected to increase by £2,500. What effect will this have on the firm’s sales?b. If PK wants to raise its price by enough to offset the effect of the increase in income, by how much must it raise its price?c. If PK raises its price by this amount, will it increase or decrease the PED? Explain.

d. What is the relationship between PK and BJ? Explain your answer.

e. If next year PK intends to charge £15 and spend £10,000 per month on promotion, while it believes per capita income will be £12,000 and BJ’s price will be £3, calculate the income elasticity of demand. What does this tell you about the nature of PK’s product?

f. What effect would an increase in advertising of £1000 have on profitability, if each additional unit costs £10 to produce?

a. Use the marginal effect of income on quantity demanded: ∆Q/∆Y = 2,8 - ∆Y = 2,5 ∆Q/2,5 = 2,8 ∆Q = 2,8 * 2,5 = 7; or 7.000 units

b. Use the marginal effect of price on quantity demanded:

∆Q/∆P = 5,4 - 7/ ∆P = 5,4 - ∆P = 7/5,4 = £1:30

c. PED = (dQ/dP)*(P/Q) = 5,4 (P/Q)

As P increases and Q stays constant (because of rising income), PED increases in absolute magnitude, meaning that demand becomes more elastic.

d. The two companies make complementary products because the marginal effect of the price of BJ on the quantity of PK is negative.

e. YED = (dQ/dY)* (Y/Q)

= 2,8 * 12/(150 - 5,4*15 + 0,8*10 + 2,8*12 - 12 *3) = 0,3140

f. If ∆A = 1; ∆Q = 0,8 = 800 units; ∆R = 800*15 = 12.000 C = 800*10 (production) + ∆A (£1.000) = £9.000

Thus every additional £1,000 spent on advertising increases profit by £3.000.