Pre-Test Question:

Chapter 6. Chapter 6 Solving Linear Equations

Math and Graphing Review
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You must read each slide, and complete any questions on the slide, in sequence.

Suppose the market for grapefruit has the following demand and supply functions:

• QD = 700 – 100P
• QS = 200 + 150P

Using these supply and demand functions, how many grapefruits will be sold in equilibrium?

A.
B.
C.
D.
Correct! In equilibrium there will be 500 grapefruits sold!
Sorry,in equilibrium there will be 500 grapefruits sold. To determine the market equilibrium price, set quantity demanded equal to quantity supplied, then solve for the equilibrium price, which is $2. At the equilibrium price of $2, the market quantity will be 500.

1.

The demand function for iPads is equal to QD = 10,000 – 25P. How many iPads will consumers demand if their price is $300?

A.
B.
C.
D.
Correct! If the price for iPads is $300, then consumers will demand 2,500 iPads.
Sorry, if the price for iPads is $300, then consumers will demand 2,500 iPads. To determine the quantity demanded, substitute $300 for the variable P and solve for QD.

2.

Suppose the supply function for tacos is equal to QS = 100 + 10P. At what price would producers be willing to supply 150 tacos?

A.
B.
C.
D.
Correct! If the price for tacos is $5, producers will be willing to produce 150 tacos.
Sorry, if the price for Tacos is $5 then producers will be will to produce 150 tacos. First, solve the supply function for P= –10+QS/10. Next, set QS equal to 150 and solve for P, to get P=$5.

3.

Suppose the hamburger market in a small town has the following demand and supply functions:

• QD = 50 – 2P
• QS = 30 + 3P

Using these supply and demand functions, what will be the equilibrium price of hamburgers?

A.
B.
C.
D.
Correct! The equilibrium price for hamburgers will be $4.
Sorry,the equilibrium price for hamburgers will be $4. To determine the market equilibrium price, set quantity demanded equal to quantity supplied and solve for the equilibrium price, to get $4.

4.

Suppose the small-town market for bubble gum has the following inverse demand and supply functions:

• P = 20 – 1/3(QD)
• P = –10 + 1/5(QS)

Using these inverse supply and demand functions, what will be the equilibrium price of bubble gum?

A.
B.
C.
D.
Correct! The equilibrium price for bubble gum will be $1.25.
Sorry, the equilibrium price for bubble gum will be $1.25. To determine the market equilibrium price,first rewrite each equation to solve for QD and QS and then solve for the equilibrium price.

5.

Suppose the demand function for coffee is equal to QD = 100 – 10P. If last week the price of a cup of coffee was $3 and this week the price has increased to $4, how many fewer cups of coffee are sold this week?

A.
B.
C.
D.
Correct! 10 fewer cups of coffee are sold this week.
Instead of the 70 cups of coffee sold last week, 60 cups are sold this week, so 10 fewer cups of coffee are sold this week.