The supply and demand curves for a product are as follows: Q d = 10560 − 80 P Q_{d}=10560-80P P = 1 40 Q s + 6 P=\frac{1}{40}Q_{s}+6 What is the equilibrium price and quantity of the product?

Alright. Let's tackle this practice problem. The supply and demand curves for a product are as follows and we are given a demand curve there first and a supply curve there second. What is the equilibrium price and quantity of the product? So right away you should notice that we do not have the same variables isolated in each equation right? On the demand equation up here, quantity demanded is by itself. For the supply equation, price is by itself. So our first step is to get the same variable isolated in both equations, and I am going to take the second equation. I don't like this fraction, I wanna get rid of it, and I'm gonna rearrange our supply equation so that quantity supplied is by itself. Alright. And remember if the problem just gave you price by itself here and not quantity demanded, right, then we're good to go. We're ready to go. If you have you know you would have price here and this would be the quantity demanded figure over here or something, then we don't have to do any of this rearranging and we're ready to just set them equal to each other, but this problem gave us tricky different isolated variables so let's go ahead and rearrange this formula right here. So we have p equals 140th qs plus 6. Alright. First step is to get rid of that 6 so we can get the qs by itself. Minus 6, minus 6. P minus 6 equals 1 40th QS. Alright and now to get the QS by itself, we need to get rid of the 1 40th. So we're dividing there by 1 40 so we need to multiply by 40 to get rid of the 1 40th. Multiply by 40 to get rid of the 1 40th. Let me do that in blue. And this side we also have to multiply by 40, right? And everything's getting multiplied by 40 not just the p and not just the 6, the whole side has to get the 40. Okay. So let's go ahead this is gonna cancel with this and we'll be left with just Qs on that side of the equation. Let's expand this out, the 40 times the p is gonna be 40p, and the 40 times the negative 6 is gonna be minus 40 times 6, 240. So 40p minus 240 is gonna equal quantity supplied. So now that we've got quantity supplied isolated here, quantity demanded is isolated over here, we are ready to set them equal to each other. Okay, so I'm gonna set that, what we just solved for equal to this quantity demanded amount over here. So 40p minus 240 equals 10,560 minus 80p. Alright so let's go ahead and add 80p to both sides. This way we stay with positive numbers, it's just easier, And we are gonna get 120p minus 240 equals 10560 and this will cancel. Right? And next we want to add 240 to each side, plus 240 plus 240. Alright. This is gonna cancel and we'll be left with 120p equals 10 800. Right? And let's go ahead and divide both sides by a 120 to get p by itself. Alright, so I can't do this math in my head. I'm gonna need a second let's see, 108100 divided by 120, it's gonna give us a price of 90. Right there. So we figured out our equilibrium price is going to be 90 and if we look at our multiple choice answers, we can see there's only one that says 90 so our work could be done but I want to just double check and that's as easy as taking this 90 and plugging it into one of our original equations. Okay so I'm going to go ahead and pick the first equation, it looks pretty easy, and I'm going to say q equals 105.60 minuteus 80 times our price that we just solved for which was 90, right. So q equals 10560 minuteus 80 times 90 is 7200 and then we just do that math, q equals 10560 minuteus 7200 is 33.60 and that is the quantity that we got there. So we've solved for equilibrium price, equilibrium quantity, the answer here is D. Great. Let's move on.

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0. Basic Principles of Economics1h 5m

Introduction to Economics
3m

People Are Rational
2m

People Respond to Incentives
1m

Scarcity and Choice
2m

Marginal Analysis
9m

Allocative Efficiency, Productive Efficiency, and Equality
7m

Positive and Normative Analysis
7m

Microeconomics vs. Macroeconomics
2m

Factors of Production
5m

Circular Flow Diagram
5m

Graphing Review
10m

Percentage and Decimal Review
4m

Fractions Review
2m

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Graphs of Two Variables
4m

Relationships between Variables
7m

Interpreting Graphs, Correlation, Causation, and Omitted Variables
6m

Slope of Linear Graphs
7m

Slope of a Curve at a Point
3m

Finding the Maximum and Minimum Points on Graphs
2m

Percentage and Decimal Review
5m

Fractions Review
12m

Areas of Shapes
8m

2. Introductory Economic Models1h 10m

Production Possibilities Frontier (PPF) - Introduction and Productive Efficiency
18m

PPF - Increasing Marginal Opportunity Costs and Allocative Efficiency
13m

PPF - Outward Shifts
8m

PPF - Comparative Advantage and Absolute Advantage
18m

PPF - Comparative Advantage and Trade
7m

PPF - The Price of the Trade
3m

3. The Market Forces of Supply and Demand2h 26m

Competitive Markets
10m

The Demand Curve
13m

Shifts in the Demand Curve
24m

Movement Along a Demand Curve
5m

The Supply Curve
9m

Shifts in the Supply Curve
22m

Movement Along a Supply Curve
3m

Market Equilibrium
8m

Using the Supply and Demand Curves to Find Equilibrium
3m

Effects of Surplus
3m

Effects of Shortage
2m

Supply and Demand: Quantitative Analysis
40m

4. Elasticity2h 26m

Percentage Change and Price Elasticity of Demand
19m

Elasticity and the Midpoint Method
20m

Price Elasticity of Demand on a Graph
11m

Determinants of Price Elasticity of Demand
6m

Total Revenue Test
13m

Total Revenue Along a Linear Demand Curve
14m

Income Elasticity of Demand
23m

Cross-Price Elasticity of Demand
11m

Price Elasticity of Supply
12m

Price Elasticity of Supply on a Graph
3m

Elasticity Summary
9m

5. Consumer and Producer Surplus; Price Ceilings and Floors3h 45m

Consumer Surplus and Willingness to Pay
38m

Producer Surplus and Willingness to Sell
26m

Economic Surplus and Efficiency
18m

Quantitative Analysis of Consumer and Producer Surplus at Equilibrium
28m

Price Ceilings, Price Floors, and Black Markets
38m

Quantitative Analysis of Price Ceilings and Price Floors: Finding Points
20m

Quantitative Analysis of Price Ceilings and Price Floors: Finding Areas
54m

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Introducing Taxes and Tax Incidence
19m

Effects of Taxes on a Market
12m

Elasticity and Taxes
14m

Subsidies
16m

The Laffer Curve
9m

Quantitative Analysis of Taxes
13m

Tax Efficiency
9m

Tax Equity
11m

7. Externalities1h 12m

Externalities: Social Benefits and Social Costs
28m

Public Solutions to Externalities
26m

Private Solutions to Externalities: The Coase Theorem
17m

8. The Types of Goods1h 13m

Four Types of Goods and Two Characteristics
28m

The Free Rider Problem and the Tragedy of the Commons
22m

Public Goods: Demand Curve and Optimal Quantity
23m

9. International Trade1h 16m

Exporting and Importing
16m

Sources of Comparative Advantage
6m

Tariffs on Imports
21m

Import Quotas and VERs
23m

Arguments Against International Trade
7m

10. The Costs of Production2h 35m

Revenue, Cost, and Profit
30m

The Production Function and Diminishing Returns
12m

Marginal Cost
27m

The Relationship Between Average Cost and Marginal Cost
23m

Graphing Costs
17m

Average Total Cost: Short Run and Long Run
19m

Isoquant Lines
9m

Isocost Lines
7m

Cost-Minimizing Combination of Labor and Capital
6m

11. Perfect Competition2h 23m

Introduction to the Four Market Models
2m

Characteristics of Perfect Competition
6m

Revenue in Perfect Competition
14m

Perfect Competition Profit on the Graph
20m

Short Run Shutdown Decision
33m

Long Run Entry and Exit Decision
18m

Individual Supply Curve in the Short Run and Long Run
6m

Market Supply Curve in the Short Run and Long Run
9m

Long Run Equilibrium
12m

Perfect Competition and Efficiency
15m

Four Market Model Summary: Perfect Competition
5m

12. Monopoly2h 13m

Characteristics of Monopoly
21m

Monopoly Revenue
12m

Monopoly Profit on the Graph
16m

Monopoly Efficiency and Deadweight Loss
20m

Price Discrimination
22m

Antitrust Laws and Government Regulation of Monopolies
11m

Mergers and the Herfindahl-Hirschman Index (HHI)
17m

Four Firm Concentration Ratio
6m

Four Market Model Summary: Monopoly
4m

13. Monopolistic Competition1h 9m

Characteristics of Monopolistic Competition
10m

Revenue in Monopolistic Competition
14m

Monopolistic Competition Profit on the Graph
13m

Monopolistic Competition in the Long Run
14m

Efficiency in Monopolistic Competition
8m

Advertising
4m

Four Market Model Summary: Monopolistic Competition
3m

14. Oligopoly1h 26m

Characteristics of Oligopoly
16m

One-Time Games and the Prisoner's Dilemma
30m

Game Theory and Oligopoly Profit
16m

Repeated Games
5m

Kinked-Demand Theory
13m

Four Market Model Summary: Oligopoly
3m

15. Markets for the Factors of Production1h 26m

The Production Function and Marginal Revenue Product
16m

Demand for Labor in Perfect Competition
7m

Shifts in Labor Demand
13m

Supply of Labor in Perfect Competition
7m

Shifts in Labor Supply
5m

Differences in Wages
6m

Other Factors of Production: Land and Capital
5m

Unions
6m

Monopsony
11m

Bilateral Monopoly
5m

16. Income Inequality and Poverty35m

Income Inequality in the USA and Worldwide
1m

Poverty
5m

Polices to Reduce Poverty
6m

Lorenz Curve and Gini Coefficient
16m

Income Equality and Efficiency
6m

17. Asymmetric Information, Voting, and Public Choice39m

Asymmetric Information: Adverse Selection and Moral Hazard
11m

Solutions to Informational Problems
11m

Median Voter Theorem
9m

Condorcet Voting Paradox
7m

18. Consumer Choice and Behavioral Economics1h 16m

Budget Constraint
27m

Indifference Curves
25m

Indifference Curves for Perfect Substitutes and Perfect Complements
4m

Consumer Optimum Consumption: Budget Constraint and Indifference Curves
7m

Consumer Optimum Consumption: Marginal Utility per Dollar Spent
13m

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Measuring National Output and Income (MACROECONOMICS)54m

Expenditure Approach for Measuring GDP
2m

Detailed Explanation of GDP Components
6m

Nominal GDP and Real GDP
22m

Calculating GDP Using the Income Approach
10m

Value Added Method for Measuring GDP
3m

Shortcomings of GDP
2m

Other Measures of Total Production and Total Income
5m

Unemployment and Inflation (MACROECONOMICS)1h 34m

Labor Force and Unemployment
10m

Types of Unemployment
12m

Unemployment: Minimum Wage Laws and Efficiency Wages
7m

Inflation and Consumer Price Index (CPI)
16m

Using CPI to Adjust for Inflation
7m

Problems with the Consumer Price Index (CPI)
5m

Nominal Income and Real Income
12m

Nominal Interest, Real Interest, and the Fisher Equation
5m

Who is Affected by Inflation?
5m

Demand-Pull and Cost-Push Inflation
6m

Costs of Inflation: Shoe-leather Costs and Menu Costs
4m

Productivity and Economic Growth (MACROECONOMICS)1h 4m

Long-Run Economic Growth
2m

Productivity and the Per-Worker Production Function
19m

Institutions that Promote Economic Growth
8m

Growth Rates and the Rule of 70
10m

New Growth Theory
6m

PPF - Growth Analysis
6m

Business Cycles and Their Characteristics
10m

The Financial System (MACROECONOMICS)1h 30m

Investment, Savings, and the Financial System
4m

Savings Equal Investment
16m

Market for Loanable Funds
4m

Shifts in the Market for Loanable Funds
15m

Stocks, Bonds, and Mutual Funds
7m

Risk and Insurance
7m

Risk and Diversification
9m

Time Value of Money Calculations
17m

Calculating Bond and Stock Prices
6m

Income and Consumption (MACROECONOMICS)57m

The Consumption Function
29m

The Saving Function
6m

Determinants of Consumption and Saving
6m

Average Propensity to Consume and Save
5m

Multiplier Effect of Investment Spending
9m

Deriving the Aggregate Expenditures Model (MACROECONOMICS)1h 14m

Aggregate Expenditures Model and Macroeconomic Equilibrium
17m

AE Model: Graphing Macroeconomic Equilibrium
13m

AE Model: Private Closed Economy
5m

AE Model: Private Open Economy
5m

AE Model and the Multiplier
11m

AE Model: Algebraic Approach
13m

Deriving the Multiplier Algebraically
7m

Aggregate Demand and Aggregate Supply Analysis (MACROECONOMICS)1h 22m

Aggregate Demand
17m

Deriving Aggregate Demand from the Aggregate Expenditure Model
12m

Shifting Aggregate Demand
4m

Long Run Aggregate Supply
9m

Short Run Aggregate Supply
7m

Shifting Short Run Aggregate Supply
8m

AD-AS Model: Equilibrium in the Short Run and Long Run
5m

AD-AS Model: Shifts in Aggregate Demand
18m

The Monetary System (MACROECONOMICS)58m

The Functions of Money; The Kinds of Money
8m

Defining the Money Supply: M1 and M2
2m

Required Reserves and the Deposit Multiplier
8m

Introduction to the Federal Reserve
8m

The Federal Reserve and the Money Supply
11m

History of the US Banking System
9m

The Financial Crisis of 2007-2009 (The Great Recession)
10m

Monetary Policy (MACROECONOMICS)1h 26m

Monetary vs Fiscal Policy
3m

Goals of Monetary Policy
3m

The Demand for Money
4m

The Money Supply on the Graph
11m

Monetary Policy and Aggregate Demand
17m

Expansionary and Contractionary Monetary Policy
15m

Taylor Rule
11m

Quantity Theory of Money
9m

Federal Reserve Policies during the 2007-2009 Recession
8m

Fiscal Policy (MACROECONOMICS)52m

Introduction to Fiscal Policy
9m

Expansionary and Contractionary Fiscal Policy
9m

Government Purchases and the Multiplier Effect
8m

Taxes, the Multiplier Effect, and Automatic Stabilizers
9m

Long Run Effects of Fiscal Policy
6m

Criticisms of Fiscal Policy
10m

Tradeoffs Between Inflation and Unemployment (MACROECONOMICS)1h 2m

Short Run Phillips Curve
9m

Long Run Phillips Curve
6m

Phillips Curve and Expected Inflation
23m

Phillips Curve and Supply Shocks
5m

Sacrifice Ratio
8m

Disinflation and Deflation
9m

Open-Economy Macroeconomics (MACROECONOMICS)1h 44m

Balance of Payments: Introduction
5m

Balance of Payments: Current Account
8m

Balance of Payments: Financial Account and Capital Account
7m

Net Exports Equal Net Foreign Investment
7m

Balance of Trade; Trade Deficit and Trade Surplus
6m

Exchange Rates: Introduction
14m

Exchange Rates: Nominal and Real
13m

Exchange Rates: Equilibrium
8m

Exchange Rates: Shifts in Supply and Demand
11m

Exchange Rates and Net Exports
6m

Exchange Rates: Purchasing Power Parity
3m

The Gold Standard
4m

The Bretton Woods System
6m

Macroeconomic Schools of Thought (MACROECONOMICS)31m

Classical Model and Keynesian Model
9m

Monetarist Model
4m

New Classical Model
4m

Real Business Cycle Model
3m

Austrian Model
3m

Communism and Karl Marx
5m

Dynamic AD/AS Model (MACROECONOMICS)32m

Dynamic AD-AS Model: Introduction
4m

Dynamic AD-AS Model: Inflation and Recession
10m

Dynamic AD-AS Model: Fiscal Policy
9m

Dynamic AD-AS Model: Monetary Policy
7m

3. The Market Forces of Supply and Demand

Supply and Demand: Quantitative Analysis

Microeconomics

3. The Market Forces of Supply and Demand

Supply and Demand: Quantitative Analysis

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Multiple Choice

The supply and demand curves for a product are as follows:
$Q_{d} = 10560 - 80 P$
$P = \frac{1}{40} Q_{s} + 6$
What is the equilibrium price and quantity of the product?

P* = \$60, Q* = 5760

P* = \$70, Q* = 4960

P* = \$80, Q* = 4160

P* = \$90, Q* = 3360

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Verified step by step guidance

Identify the demand equation: Qd = 10560 - 80P, where Qd is the quantity demanded and P is the price.

Identify the supply equation: Qs = 140P + 6, where Qs is the quantity supplied and P is the price.

Set the quantity demanded equal to the quantity supplied to find the equilibrium: 10560 - 80P = 140P + 6.

Solve the equation for P to find the equilibrium price. Combine like terms and isolate P on one side of the equation.

Substitute the equilibrium price back into either the demand or supply equation to find the equilibrium quantity.

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The supply and demand curves for a product are as follows: Qd=10560−80PQ_{d}=10560-80PP=140Qs+6P=\(\frac{1}{40}\)Q_{s}+6 What is the equilibrium price and quantity of the product?

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Supply and Demand: Quantitative Analysis practice set

The supply and demand curves for a product are as follows:
$Q_{d} = 10560 - 80 P$
$P = \frac{1}{40} Q_{s} + 6$
What is the equilibrium price and quantity of the product?