2011 AMC

[JSGandora]

I winged the 10A and got a 126. XP I answered 21 questions and got the chord probability one wrong because of a stupid mistake...and I thought I was being clever...

[quadratic]

O.K. I had the wrong name but ocarina appeals to plenty of people and deserves a thread

[Skystrider]

The first thing I thought when I saw the title of this thread was, "Chrysler is bringing the Gremlin and Pacer back?" The reality is probably preferable.

[RandomPerson]

O.K. I had the wrong name but ocarina appeals to plenty of people and deserves a thread

Quadratic, on a gaming forum, especially those dedicated to nintendo consoles that could be justified. In general, when a forum concentrates on something completely different than video games (especially if it isn't even tangentially related) a thread on anything specific with video games is not deserved. A thread on the general subject of video games is.

That is confusing so let me explain with another example, say there is a cooking forum, a thread on science olympiad (despite how awesome it is) would not be deserved because it is specific and not related enough to cooking. A general topic on the sciences or even one on biology, chemistry, or physics may be deserved because it is broad enough.

But let me give you some advice, you are making a bad name for yourself and you are a new user. You made a thread on ocarina of time and we told you that it was not appropriate for the forums. Your indignation that it is, and your repeated spitefulness about it being locked is incredibly annoying, and comes off as very arrogant.
If you want to be respected here: drop it even if you think it was entirely justified, we've made it clear we don't think it is. Cleaning up your spelling and grammar wouldn't hurt either.

On the subject of the AMC, I took the AMC 12. I usually approach the exam not caring because I'm not a math wiz like the rest of you, I consider myself very competent at math, but the exams are out of my league. I'd be farily happy with a 60 frankly.
Anyway, I got an 87 to my surprise, a bit of luck was involved.

[quadratic]

OK

[lllazar]

I'm psyched about my score on the 10 (129), though i do feel kinda stupid about #21. I was rushing at that point (had 15 minutes after finishing #20) and i took a look at 24 and 25 the moment the test started - MONSTERS. To anyone who got above a 141, major props cause you got some really hard problems under the time pressure. I don't know how much a 133.5 would have helped me versus a 129 (if i had gotten 21) though, so w/e...None the less, 1-20 seemed relatively routine, and #21 as well to a certain extent (if you had a general understanding of combinatorics), it was those last few that freaked me out.

Im thinking index for USAJMO will be around 200+ this year so i need an 8 on AIME to make it....good luck to everyone who qualified for AIME, and everyone else on their AMC scores as well!

[Teal]

^ You're going to do super well!
Did you figure out the $17.71 one? I couldn't at all. I just gave up on that one.

[winneratlife]

I'm psyched about my score on the 10 (129), though i do feel kinda stupid about #21. I was rushing at that point (had 15 minutes after finishing #20) and i took a look at 24 and 25 the moment the test started - MONSTERS. To anyone who got above a 141, major props cause you got some really hard problems under the time pressure. I don't know how much a 133.5 would have helped me versus a 129 (if i had gotten 21) though, so w/e...None the less, 1-20 seemed relatively routine, and #21 as well to a certain extent (if you had a general understanding of combinatorics), it was those last few that freaked me out.

NICE

I don't know, I just had a brain freeze on 21 and 22, in restropect they seemed so simple to me, but sitting there I just couldn't get them. And I screwed up 14.

Did you figure out the $17.71 one? I couldn't at all. I just gave up on that one.

To solve that one, you had to recognize that 3 factors were needed: the pencils cost cents each, there were students, and each student bought pencils.

Now, from the problem, we know:





So we prime factorize 1771. Looking at it, with divisibility rules for 11, it is divisible by 11 (every other digit adds up to 8), and so we get . To divide 161, just try uncommon primes (it is not divisible by 2, 3, or 5, as shown by the rules for those numbers). Some experimentation gives .

So we now know:






Plugging in one each of 7, 11, and 23 for x, y, and z, so that they fill the above parameters, it seems that . Following that, since , and

EDIT: If you guys want, I can post the solution to 25.

[blue cobra]

I'm guessing you had y students buying z pencils at x cents each and the total price was $17.71, so xyz=1771 (because x is in cents)? If so, why would you need the prime factorization of 1771, rather than anything else. As well, did you know 1771 would have three prime factors, or did you predict that it would and then found out you were right?

I didn't take this (my school doesn't offer it, nor do local colleges, not that I'd do that well anyway) but what difficulty level is this, if you can find an appropriate yardstick?

[winneratlife]

I'm guessing you had y students buying z pencils at x cents each and the total price was $17.71, so xyz=1771 (because x is in cents)? If so, why would you need the prime factorization of 1771, rather than anything else. As well, did you know 1771 would have three prime factors, or did you predict that it would and then found out you were right?

Best yardstick: Last year's B test:http://www.artofproblemsolving.com/Foru ... b9d6d851f8

Also, in general, the "proper approach" to solving xyz = a is to always prime factorize a first, then figure out where to go from there. I don't know; it just works.