Sunday, March 02, 2008

Dreaming of Espresso

A double espresso with milk would be absolutely amazing at the moment. Drained doesn't even describe the feeling at the moment. I spent my break today solving random equations on finding the equilibrium price and quantity of each. I reviewed both of the topics, then went over the section about black market profits. I then timed myself to see how fast I could solve each equation with it's multiple parts. I got my time down from 11mins to 6mins to 5 mins to finally 3mins. Then I tried to solve the final equation which introduced Black Market Profits and my time jumped back up to 7mins - and on top of that the answer I came up with was totally wrong.

Those of you who know me are probably wondering what the heck is going on.. well yes this is me actually "talking" about math. Amazingly I am starting to get the hang of it and actually find solving equations and getting the "correct" answer somewhat satisfying... In the end though I do feel like I am progressing alot (huge thanx to BW) it doesn't really cover the very vivid truth though.

Truth is, I'm worried - with all due right of course. Tomorrow is the feared Business Math midterm. I've been working my ass off for it and still end up making little stupid mistakes that add up and mean big mistakes. I thought I had at least scored a 10/20 on my last math quiz (quiz 2). I got the paper back today and was pretty surprised to find otherwise. I had practiced even more on Thursday evening (with BW) and on most of Friday, so I figured now I must be able to spot my mistakes. I couldn't wait till class ended so I could sit down and try and come up with the correct answer without having to ask BW what my mistake was.



This is what quiz 2 looked like. It started with this equation:

P = -2Q + 50

P = 1/2Q + 25

a) Determine the equilibrium price and quantity.

b) Calculate the tax paid by the consumer and by the producer.

This is what I did (after the teacher marked my paper 8/ 20 [4 mark improvement over 4/20] ):

P = -2Q + 50 = 1/2Q + 25

50 – 25 = ½ Q + 2Q

25 = 2.50Q

25/2.50 = 2.50Q/2.50


My original mistake had been calculating 25/2.50 in my head, and somehow 2.50 being half of 5 became half in my head so I solved it as 25/0.5 . So fine this time I caught my original mistake, but then when I got to finding the equilibrium price I found something else wasn't right.

Pd = -2Q + 50

= -2(10) +50

= 20 + 50

Pd = 70

Ps = ½ Q + 25

= 0.5(10) + 25

= 5 + 25

Ps = 30

In the end Pd is supposed to equal Ps.. I couldn't understand why the hell that wasn't happening. I thought about it for a while and wondered if maybe the original equation was supposed to read:

P = -2Q - 50

P = 1/2Q + 25

I tried the new "fixed" equation and came up with:

P = -2Q – 50 = ½ Q + 25

= -2 Q – 50 = 0.5Q + 25

= -25 – 50 = 0.5 + 2Q

= 25/2.50 = 2.50Q/2.50

10 = Q

Pd = -2Q – 50

= -2(10) – 50

= -20 – 50

= 30

Then both equations (Pd & Ps) would come down to the same thing (30). And the answer to part (a) of the quiz would have been

Equilibrium Price = 30
Quantity = 10

So now my question is: did the teacher really make a mistake like that???

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