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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1. Introduction to Macroeconomics2h 13m

Introduction to Economics
12m

Three Key Economic Ideas
15m

Productive and Allocative Efficiency
8m

Factors of Production
6m

Positive and Normative Analysis
8m

Circular Flow Diagram
6m

Graphing Review
51m

Percentage and Decimal Review
10m

Fractions Review
13m

2. Introductory Economic Models1h 15m

Production Possibilities Frontier (PPF) - Introduction and Productive Efficiency
19m

PPF - Increasing Marginal Opportunity Costs and Allocative Efficiency
12m

PPF - Outward Shifts
9m

PPF - Comparative Advantage and Absolute Advantage
14m

PPF - Comparative Advantage and Trade
14m

PPF - The Price of the Trade
4m

3. Supply and Demand3h 28m

Introduction to Supply and Demand
5m

The Basics of Demand
7m

Individual Demand and Market Demand
3m

Shifting Demand
39m

The Basics of Supply
3m

Individual Supply and Market Supply
6m

Shifting Supply
29m

Overview of Supply and Demand Shifts
9m

Supply and Demand Together: Equilibrium, Shortage, and Surplus
6m

Supply and Demand Together: One-sided Shifts
20m

Supply and Demand Together: Both Shift
34m

Supply and Demand: Quantitative Analysis
41m

4. Elasticity2h 36m

Percentage Change and Price Elasticity of Demand
19m

Elasticity and the Midpoint Method
21m

Price Elasticity of Demand on a Graph
12m

Determinants of Price Elasticity of Demand
7m

Total Revenue Test
14m

Total Revenue Along a Linear Demand Curve
15m

Income Elasticity of Demand
24m

Cross-Price Elasticity of Demand
12m

Price Elasticity of Supply
13m

Price Elasticity of Supply on a Graph
4m

Elasticity Summary
10m

5. Consumer and Producer Surplus; Price Ceilings and Price Floors3h 19m

Willingness to Pay and Consumer Surplus
19m

Willingness to Sell and Producer Surplus
13m

Economic Surplus and Efficiency
19m

Quantitative Analysis of Consumer and Producer Surplus at Equilibrium
29m

Price Ceilings, Price Floors, and Black Markets
39m

Quantitative Analysis of Price Ceilings and Price Floors: Finding Points
21m

Quantitative Analysis of Price Ceilings and Price Floors: Finding Areas
55m

6. Introduction to Taxes and Subsidies1h 53m

Introducing Taxes and Tax Incidence
20m

Effects of Taxes on a Market
15m

Elasticity and Taxes
15m

Subsidies
17m

The Laffer Curve
9m

Quantitative Analysis of Taxes
14m

Tax Efficiency
9m

Tax Equity
11m

7. Externalities56m

Externalities: Social Benefits and Social Costs
28m

Public Solutions to Externalities
27m

8. The Types of Goods1h 6m

Four Types of Goods and Two Characteristics
23m

The Free Rider Problem and the Tragedy of the Commons
23m

Public Goods: Demand Curve and Optimal Quantity
19m

9. International Trade1h 21m

Exporting and Importing
17m

Sources of Comparative Advantage
6m

Tariffs
22m

Import Quotas and VERs
24m

Arguments Against International Trade
8m

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 26m

Introduction to the Four Market Models
2m

Characteristics of Perfect Competition
6m

Revenue in Perfect Competition
14m

Perfect Competition Profit on the Graph
21m

Short Run Shutdown Decision
35m

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 Poverty36m

Income Inequality in the USA and Worldwide
1m

Poverty
5m

Polices to Reduce Poverty
6m

Lorenz Curve and Gini Coefficient
17m

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

3. Supply and Demand

Supply and Demand: Quantitative Analysis

Microeconomics

3. 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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Struggling with Microeconomics?

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?