October 2010 Math SAT Thread

Test Preparation SAT Preparation
941

<p>@Jetscm </p>

<p>Here’s my clear response to argue for 1/54. </p>

<p>When you calculated the 216 possibilities, you did so doing a permutation (x<em>x</em>x…). Because it is a permutation, the order of the numbers is important, and creates distinct values. In this case, that means that 656 != 665 != 566. All three of those are distinct values, that are included in the 216 possibilities. Because those 3 are all part of the 216, then they also have to be considered when you’re doing the probability that they will appear.
It’s unfortunate 1/6<em>1/6</em>2/6 gives the wrong answer, because that’s a more logical and mathematical approach than writing out all the possibilities that the sum be equal to 17 or 18…
But hell, I could be wrong too. It’s just my two cents. We’ll all know on October 28th :)</p>

942

<p>For the 1080 question do you guys remember the answer choices i remember 5400 and 1080 being them but what about the others.</p>

943

<p>@jetscm4ev
This link shows the probability of the dice problem:
<a href=“https://alumnus.alumni.caltech.edu/~leif/FRP/probability.html[/url]”>https://alumnus.alumni.caltech.edu/~leif/FRP/probability.html&lt;/a&gt;&lt;/p&gt;

<p>Look at the first chart; in the column for 3 dice, look at the probability for rows 17 and 18. 17 is 3/216 and 18 is 1/216. Since the question asked “a sum of 17 OR 18”, you add, so it is 4/216 (1/54).</p>

944

<p>what is the math experimental? can someone talk about some questions that were from there?</p>

945

<p>owlehn, it cannot be 1/108.</p>

<p>“You have three dice. What’s the probability that the sum of the three numbers rolled is 17 or 18?”</p>

<p>you have 216 possible rolls because of 6x6x6=216</p>

<p>then four rolls will give you 17 or 18
556 656 655 666</p>

<p>216 divied by 4 = 1/54</p>

946

<p>Did anyone else get these questions? I notice no one has mentioned these at all, I think they are an experimental section:</p>

<ol>
<li>What is the perimeter of a triangle with sides a,b, and c if:</li>
</ol>

<p>2(a+b) + c = 38
2(a+c) + b = 40
2(b+c) + a = 42</p>

<ol>
<li>What is the number of combinations of a 3-digit number that is less than 600 that can be made from the numbers 3,5,7, and 9?</li>
</ol>

947

<p>Does the order of the dice matter? I don’t think so. No where in the question did it specify that the order of the dice matter… therefore 655 and 666 are the possible combinations. (2/216) = (1/108)</p>

948

<p>what do you think the score for 1 wrong and 1 skip will be?</p>

949

<p>1 wrong and 1 skip will be a 760, I believe. 750 or 760.</p>

950

<p>"Does anyone remember the exact equation in the question with an answer like </p>

<p>x^2 < 3/5 y^2
or something like that? That’s the only question I’m concerned about, I really hope I didn’t misread something"</p>

<p>I remember that question. It was a matter of wheter the lessthan-greaterthan sign flips when you use division. I think I answered with the flipped one but I am not sure if I am right.</p>

951

<p>argh…ok thanks. i was hoping for a 770+ but i guess not…</p>

952

<p>My experimental was math and it had a question about kids bringing something to school and it had a chart with 0 kids bringing 3 items, 1 kid bringing like 4 items etc. The question was how many items could 4 kids bring so that the total mean was greater than the median number. Did anybody get a question like this because im sure it was like number 17 in the experimental math.</p>

953

<p>It only flips if you divide by a negative number. I’m pretty sure the question stated that x and y were both positive integers, which would mean the sign doesn’t flip</p>

954

<p>we are missing a grid in on the consolidated list. 1080 is listed as one when its really an MC.</p>

955

<p>what was the answer to the band question; I thought it would be 5*4! because the different leaders and then 4 would be in whatever order.</p>

956

<p>The band questions was 24.</p>

957

<p>we need a final consolidated list.</p>

958

<p>but why was it 24 I thought any one could be a leader and then the four others would be random.</p>

959

<p>^ then four rolls will give you 17 or 18
556 656 655 666</p>

<p>216 divied by 4 = 1/54 </p>

<p>5+5+6 = 16 if i’m not mistaken</p>

960

<p>Look at post #953, was this question in an experimental section or not</p>