A few days ago
Steph

MATH LOVER- help! pretty plz?

This is for my economics HW, I’m having a little trouble w/ this problem so plz tell me the answer and how you got that answer. THNKS!

1. In the small town of Negreanu, there is a competitive market for decks of playing cards.

Suppose that the demand curve is a straight line and is given by the following equation:

P = 9 – (2/3)QD, where P is the price per deck and QD is the quantity demanded per day.

The supply curve is also a straight line and is given by the following equation:

P = 2 + (1/2)QS, where P is the price per gallon and QS is the quantity supplied per day.

The equilibrium price per deck of cards equals ____, and the equilibrium quantity equals _____.

A. $7; 3 decks of playing cards

B. $5; 6 decks of playing cards

C. $6; 6 decks of playing cards

D. $5; 4 decks of playing cards

Top 2 Answers
A few days ago
math guy

Favorite Answer

The equilibrium price is the price where the two lines cross. Keep in mind that when at equilibrium, QD = QS, so I will just use Q to represent both.

So:

P = 9 – (2/3)Q and P = 2 + (1/2)Q

Then:

9 – (2/3)Q = 2 + (1/2)Q

7 = (2/3 + 1/2)Q

7 = (7/6)Q

Q = 6

Plug this into either of the equations you gave us to get:

P = 2 + (1/2)*6

P = 2 + 3

P = 5

So B: $5; 6 decks of playing cards

I hope this is all clear!

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A few days ago
Kara Lee
I’m assuming that you know how to graph regular lines, if not, I’m sorry, but this won’t help you.

Treat P like a Y, and treat QD and QS like an X.

Your equations become:

Y = 9 – (2/3)X

Y = 2 + (1/2)X

If you graph these lines, you can see they cross at about B. $5, 6 decks.

Also, you can confirm this by plugging these values into the equations. (Plug 6 in for QD and QS and see that they both work out to equal 5) Hope this helped. Good luck!

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