KMO Spring

NotjustoldWASPs · Post by **NotjustoldWASPs** » Wed Apr 26, 2006 8:47 pm

Ok, it's 8:45 and Im quite surprised no one has posted on this yet:

How did y'all (yes, I can say this...I'm from Virginia) do on the KMO?

TJ score: 1755

...and was it just me or did the question difficulty seem much harder than the fall? And I'm fairly sure there was an awful error in one of the math problems (probability of two different colored balls). Anyway, comments and such would be appreciated.

Post by **DumbJaques** » Wed Apr 26, 2006 9:01 pm

RM: 1711

My math guys were pretty sure that math question was bogus too. As for the questions, definitely harder than fall, but I thought fall was on the easy side.

EDIT: State College got 1763

fancynancy · Post by **fancynancy** » Wed Apr 26, 2006 9:03 pm

I thought there was something weird about that ball question...

DrakeRQB · Post by **DrakeRQB** » Wed Apr 26, 2006 10:20 pm

This semester was harder, but our young team improved by nearly 100 points.

Robinson scored 1209. Too many first-chance misses, but oh well. We just consider it something fun to do.

jbarnes112358 · Post by **jbarnes112358** » Wed Apr 26, 2006 10:40 pm

Maggie Walker's score was 1667 if memory serves. That is close anyway. We had a couple of key people missing, especially in the math area, but not a bad score for us, Yes, it seemed a little more difficult than in the fall.

If TJ did not win that will be news given TJ's incredible run in this competition.

rchschem · Post by **rchschem** » Thu Apr 27, 2006 7:36 am

Raleigh Charter scored 1711. Don't see ties very often. KMO settles these by # correct or first chance, right?

Eric

ProsperoSMS · Post by **ProsperoSMS** » Thu Apr 27, 2006 7:51 am

Saint Mary's got 1215--we've tended to have much better fall scores than spring ones (often because it's easier to get our core there and focused in the fall), and I really wasn't around for much to compare the questions. I'll be interested in comparing average scores.

Irreligion in Bangladesh · Thu Apr 27, 2006 9:12 am

The ball problem was fine...I'm gonna discuss it because there shouldn't be anyone left who hasn't done the test yet.

10 balls, 4 blue and 6 yellow. Find prob of 2 balls being drawn without replacement that are diff. colors.

You have a 4/10 chance of drawing blue first, then a 6/9 chance of drawing yellow second. Based on the multiple trials rule, these are then multiplied, which allows the order not to matter, it'll just switch the 6 and the 4 around. 4/10 * 6/9 is 24/90, which reduces to 4/15.

Wall of Ham · Post by **Wall of Ham** » Thu Apr 27, 2006 9:44 am

The math question was wrong, I'm pretty sure of it.

You can draw both a blue first and then a yellow OR a yellow and then a blue.

Since "or" means add, the probability of drawing different balls is-

4/10 * 6/9 (P of drawing a blue* P of next drawing yellow) + 6/10 * 4/9(P of drawing yellow * P of drawing a blue)

= 24/90 + 24/90 = 48/90 = 8/15

Or you can do it backwards and say its 1 - (the probability that the two balls are equal)

Which is just 4/10 * 3/9 (P of drawing a blue * P of drawing another blue) + 6/10 * 5/9 (P of drawing yellow * P of drawing another yellow)

= 12/90 + 30/90 = 42/90 = 7/15

1 - 7/15 = 8/15

You can even use permutations and say you can pick one blue and one yellow or 4 * 6 = 24 possible different pairs out of the total amount of pairs possible which is just 9 choose 2 or 9! / (7! * 2!) = 45

24/45= (Total different colored pairs)/(Total possible pairs) = 8/15

It also makes more since in that about half the time you draw different balls and half the time you draw the same colored ball. 8/15 is the right answer, I'm pretty sure of it.

Sorry about beating a dead horse. I love probability. I went to CTY's
Probabilty and Game theory Class.

Plus, I'm a nerd. HAh.

conker · Post by **conker** » Thu Apr 27, 2006 10:55 am

Shanghai American School scored 1637. We could have broken 1650, if the freshmen in the back of the room hadn't been HUSHED by a sophomore. I'm still pretty angry upset about the whole situation, as she certainly didn't contribute as many points as she cost. Oh well, we are still very pleased with our score, and it represents an improvement of 37 points from the fall.

mrs. dalloway · Post by **mrs. dalloway** » Thu Apr 27, 2006 5:47 pm

So...if I'm not mistaken, Rockford Auburn scored 1831.

Summoned Skull · Post by **Summoned Skull** » Thu Apr 27, 2006 6:07 pm

Decatur Eisenhower (IL) scored 1286.

jbarnes112358 · Post by **jbarnes112358** » Thu Apr 27, 2006 6:36 pm

BLiu wrote: 8/15 is the right answer, I'm pretty sure of it.

I agree with you BLiu.

A probablity tree works nicely, too.

There are four mutually exclusive outcomes for the two draws represented by branches of the tree: YY, YB, BY, and BB. Just sum the probabilities for the YB branch and the BY branch. (24/90+24/90)

pakman044 · Post by **pakman044** » Thu Apr 27, 2006 8:12 pm

The results are now out at the usual location. The average score was 1195, and this year's top score (as mentioned earlier) is 1831 from Auburn High School.

Code: Select all

                                     Score Correct Second Chance
      1 Auburn  (IL)                 1831  195      7
      2 State College (PA)           1763  196     13
      3 Thomas Jefferson (VA)        1755  193     14
      4 Saint Thomas Academy (MN)    1725  196     11
      5 Champlain Valley Union (VT)  1723  198     17
      6 Raleigh Charter (NC)         1711  196*    18
      7 Richard Montgomery (MD)      1711  191     14
      8 Laude Horton Watkins (MO)    1708  194     15
      9 Walton (GA)                  1699  193     15
     10 Ames (IA)                    1685  194*    22
*Ties broken by number of correct responses

Patrick King

First Chairman · Post by **First Chairman** » Thu Apr 27, 2006 8:19 pm

mrs. dalloway wrote:So...if I'm not mistaken, Rockford Auburn scored 1831.

Yipes... and why aren't you guys going to nationals?

fancynancy · Post by **fancynancy** » Thu Apr 27, 2006 9:37 pm

mrs. dalloway wrote:So...if I'm not mistaken, Rockford Auburn scored 1831.

Colleen, you people are crazy-amazing. Congratulations!

brownboy79 · Post by **brownboy79** » Thu Apr 27, 2006 9:43 pm

1831?
wow. just wow.
Dunbar got 1666 but our score was hurt by seniors shushing sophomores.

harpersferry · Post by **harpersferry** » Fri Apr 28, 2006 8:57 pm

Dr. Chuck, we're not going to nationals because of graduation being that same weekend. Since 5 of 8 regular varsity players are seniors, that's a bit of a deal breaker.