AMC? Mathematical Competition? (3 Viewers)

[Grey Council]

Hrm, how did people go?

how many questions are you quite sure you got out, and how many did you think you got wrong?

What do you think the cut off marks will be for prize, medal, hd, d etc?

 

[Grey Council]

myself, I think I got out 22/30, with 1 question from the last section wrong.

hrm

last year I got out 14ish, from memory, and I got a d. 17 was general cut off, I think.
remember, its all based on points, but I'm talking questions, so i might be a bit off. oh well

*refrains from commenting on GUESS WHO got full marks*

 

[Xayma]

Was that the one today, if so Im pretty sure I got 19/20 for the first 20 correct, and the other one I wasnt too sure but I had crossed out two.

And maybe 3 out of the last one.

 

[Iota]

21/30, with no questions wrong. That's a guess based on how I feel I went, and with my answers compared to other people's answers.

People tell me I should have done the square with a cut corner question in the last 10, since it was easy. I didn't even read it. =/

I'll be happy with a distinction.

 

[Rorix]

20/20 for 1,2 section afaik, attempted 5 of the last section including that incredibly easy cube question=), answer to the x^2 + bx + 2 was wrong but i still can't work out what was wrong with method, so 4/5 last section probably

 

[ngai]

*refrains from commenting on GUESS WHO got full marks*

lol wat did he say about it?...easy?


far out stupid COINS, put 540
and also miscounted the rubbing off numbers
so i'm hoping for 10,9,6

cut offs..for prize think its ~110 usually?
medal maybe 135 or so

 

[Iota]

It wasn't 540?

And what was the answer to the x^2 + bx + 2 question?

 

[ngai]

no it wasn't 540, get 3 coins out and try...its 1080
umm...
for x^2+bx+2 = 0
x = (-b +- sqrt(b^2-8))/2
so the difference between roots is sqrt(b^2+8)
and this difference > 2, and < 5 coz of the 3 integers
so 2 < sqrt(b^2-8) < 5
4 < b^2 - 8 < 25
12 < b^2 < 33
so b = +-4, or +-5
on testing, only +-4 works, so answer is 2

 

[Grey Council]

you sure? I think it was 540.

six coins can be fitted around that coin. draw up a hexagon, and you'll only be able to do 3 sides per coin. that makes it: 3x60x3
which is 540

hrm, I'll hafta ask Him.

btw, did anyone else think the last question was incredibly easy?

btw, if a certain someone gets a perfect score this year again, then he'll be the only one to have ever gotten three perfect scores running. second to get three

 

[gman03]

Oh the lovely AMC.... unfortunately yr 12 was my only year which I got a D in.

Anyone kind enuff to post the last 10 questions once you got the questions back? Senior division preferred

 

[Grey Council]

lol, I've recieved a D EVERY year since year 3, except year 3 and year 6. Every single year, I get to 97% percentile, so basically, if I get one more right, I'd get a HD.

DAMN IT! @_@

lol, most people here would be getting prizes though.
*looks at Ngai*
oh
*DOESN'T look at Archman*
*cough*

harumph, some people make silly mistakes and don't get full marks, and I don't know how to do the majority of the last section. :-( aiii, what a big difference, hrm?
ah well

 

[withoutaface]

I did 23 questions, only guessed one of the first 20 (q19), and also I think I got at least 2 of the three i answered in the last section. I'm ashamed that I only answered the same number as I did last year.

And as for the coin question, it rolls half way around each of the three other coins. :. 3*180=540

And for that question involving the arrangement of coloured tokens, I got that each could only have a line of seven, what did everyone else get?

Last year I got top 3%, years before that I got top 3-4%. I WANT MY HD DAMMIT!

EDIT: Oh and did anyone get q 19 out?

 

[ngai]

aiya, coins...
our teacher got four coins out and rotated one around the other three
and showed quite clearly that it went around three full revolutions, so 3*360 = 1080
he thought it was 540 too, but then the real experiment can't be wrong

yeah i got max line of 7 tokens

 

[withoutaface]

aiya, coins...
our teacher got four coins out and rotated one around the other three
and showed quite clearly that it went around three full revolutions, so 3*360 = 1080
he thought it was 540 too, but then the real experiment can't be wrong

yeah i got max line of 7 tokens

I'm mystified as to the mathematics of it then...

 

[Rorix]

q19 was the a + 1/(b+ 1/c) = 37/16?
a=2,b=3,c=5

 

[Xayma]

If you want to know how to do it:

a+1/(b+1/c)=37/16
As they are all integers
a+1/(b+1/c)=2+5/16
&there4; a=2
b+1/c=16/5
b+1/c=3+1/5
b=3, c=5

&three4; a+b+c=2+3+5=10

 

[Iota]

No, it was definitely 540 - and I didn't even use hexagons. Further proof that it was not 1080 is given in my diagram.

Question 19 had me stumped, but then I thought to myself "well, let's guess. Take the number 10. It's got 3 integers - 2,3,5. Maybe it'd work. And yes, it is even a possible solution. But I ignored it and went back to it latter when I'd done the other questions.

It turns out that a + 1/(b+1/c)=37/16 works when the values 2,3,5 are placed into this.

However, the way I worked it out was that 37/16 must be like 32/16 + 5/16, and comparing that to the LHS, gives a=2, 1/(b+1/c) = 5/16. So take the reciprocal of both sides to get b+1/c = 16/5, which is 15/5 + 1/5, comparing that to the new LHS gives b = 3, 1/c = 1/5. Reciprocal: c = 5.

 

[QuaCk]

Well, 19/20 for first 2 sections ...
q19 i had a total guess :|
attemped 5 of last section.
pretty sure i got questions 21,23,26,27 right.
and how the hell do you do the circle in a square questions?
i'm feeling pretty dumb here as a fair few of you guys have said this was easy :/

*hopes for HD if possible

 

[abdo]

can someone post the last few questions please? didn't do the exam

 

[Rorix]

no guys, the answer you're thinking of is a=2, b=3, c=5