You are Here: Home

# Help needed quickly watch

1. Ok so I understand the basic concepts of supply and demand but the thing that is really tripping me up is the equations.

I have: Qs = 2p, Qd = 12 - p

I know that I should be plugging in values so this what I've done.

Qd = 12 - p
2p = 12 - Q
P = 12- Q divided by 2
P = 6 - 0.5Q

so when plotting on the graph for every 6 I go up I go 3 along...correct??

so for Qs = 2p:
Q = 2x6 (since P = 6)
Q = 12....Woohoo I think explaining it made me understand it more :O.

Ok so now my next problem is that I know that Q = 12. How do I find the equilibrium price by drawing?

Well I know it is where it hits the supply line but how do I draw the demand line?? can it hit the supply line anywhere? or should I be aiming to hit it at P meaning 6?
2. anyone?
3. What you need to note is that with the equation Qd = 12 - p, 12 is the quantity demanded at which price is 0. Knowing this, you have one point in your axis that you can plot. Your next step is to find the price at which Quantity Demanded is 0, to do this you substitute Qd with 0 to get the following: 0=12-p, hence p=12 when the quantity demanded is 0. After this, substitue a random price inbetween 0 and 12, such as 6 to get a third point. Qd=12-6, Qd= 6. Now you have 3 points on your graph that should form a straight line if you join them all up.

With Qs = 2p, it simply means the quantity supplied will always be twice the price. At p=0, Qs = 0. p=1, Qs = 2. p=3, Qs = 6. And so on.... Knowing this you can plot your supply curve.

If you've plotted them correct, these two curves should intersect where P=4

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: April 1, 2013
Today on TSR

### Buying condoms for the first time - help!

Discussions on TSR

• Latest
Poll
Useful resources
Discussions on TSR

• Latest

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE