October 2011 - Math Level II

<p>do you guys remember the one where it was like “least square linear regression”?..what does that mean T_T i ended up skipping that one after trying to find a “linear regression” …and failing >.>
and how would you do the post office one (i think the other person was walking away from it or something)?..is there like a quick, “cheat” way or something to do with rates of movement since one was moving faster?
oh and how do you do the probability one with the sums? (agh probability questions always annoy me -.-)</p>

<p>i’m mad D:< since the chord one came to me as soon as i walked out the school and got a breath of fresh air (thnx brain for being so delayed -.-)…and i got the periodic one wrong because i’m an idiot and didnt know that 0 was an even integer T.T </p>

<p>whats 5 skipped, 1 wrong?
do you think the curve would be harsher or nicer?..besides the annoying questions that i skipped …it felt a lot better than when i took it in may last yr (and that one i completely BOMBED) …but i have the tendency to do stupid things and fall for their traps …so i think i should pack my bags up and run away from home at this point lol -_____-"</p>

<p>what exactly was the whole question for least square linear regression question? i can’t remember the details</p>

<p>How do you solve problems with two absolute values? How do you solve problems with cones that have different heights? How do you graph tan squared of x -1? How do you solve a problem where someone is going due north and someone is going due east at different rates? how do you simplify the expression (taking the ln of boths ides) for the exponent? Thanks for the help.</p>

<p>The linear regression one was something about the relation of gram of sodium and calories from fat in fast food or something? anyway the data table was…</p>

<p>9 …80
12…110
23…210
13…120
30…270
18…160
8…70</p>

<p>put those in l1 and l2 respectively. stat>calc>4>Vars>y-Vars>1>1>Enter… that stores the linear regression equation in y1… then clear>vars>yvars>1>1>(21) and it comes out to 189.7119 ~ 190</p>

<p>@wizkid.
you had 2 cones and it was given that they were similar. the height of one of 5 and one was 10 so the ratio was 2:1. That means the ratio of the radii will be 2:1 also. The volume of the smaller one was 15 so solve V=1/3pi(r^2)h for r since we know everything else. you get r of the small one = 1.692568 ish. the cones are in a ratio of 2:1 so double that for the radii of the larger cone = 3.3851375 ish. Now you have everything. Use the formula again and V of the large one comes out to 120.</p>

<p>For the Post office problem I set up an equation and graphed it for the minimum. The equation was: srtroot (((4-10t)^2)+(2+5t)^2)
the minimum comes out to be .2400</p>

<p>for the one that was 7^a and 49^b (yes they were number but i dont remember them)
I believe the answer was a =2b was the only incorrect one</p>

<p>@wizkid</p>

<p>The absolute value one with absolute values on both sides is 0 solutions(im still banging my head against the wall because i said 4 lol) becuase theres a negative sign before the 2nd side of the absolute value. So since the 1st side can never be negative and 2nd will always be negative, 0 solutions.</p>

<p>Graph tan squared of x-1 by putting in calculator (tan(x-1)squared. </p>

<p>Curve will probably be 44/50 or 43/50 for minmum 800</p>

<p>@Compsci: But what if you make both sides equal zero? I graphed them, and I kept getting one solution.</p>

<p>^Hm… never considered that… good observation. Are the x’s the same when u set both to 0? Dont matter anyway lol I still got it wrong</p>

<p>I guess it is 1… then half the people here are wrong lol.</p>

<p>@ankitp4t3l: …I think you’re right. Sigh, that makes 3 omit 3 wrong for me.</p>

<p>^Not as bad as I did</p>

<p>5 omit, 3 wrong</p>

<p>I didn’t think it would be this difficult. =| I’m really upset because I skipped the area of a triangle question where all you had to do was absinC/2</p>

<p>^ Lol im upset because I wasted time on that question, having forgotten the easy formula, I decided to use Heron’s formula of sq root(semiperimeter * (semi - 1st side) * (semi-2nd side) * (semi-3rd side)) and to find the perimeter i used law of cosines to find 3rd side… So stupid lol</p>

<p>Actually having taken Barrons’ tests, these were relatively easy in comparison(although time-consuming near the end), but since I failed every time at Barron’s tests…</p>

<p>@ankitp4t3l (Post #346) - Although that strategy does make sense, I think what matters more is what happens in the original equation. If you got that one solution and put it into the original equation, I don’t think it would work, so I don’t believe 1 would be the correct answer.</p>

<p>^Apparently he graphed it and it gave him one solution. But you do have a point. If it was like |x+7| = -|3x+6|, that wouldn’t be the case. So… It all depends on what the equation was. =|</p>

<p>I did the linear regression a much simpler way, if you start at 18 and end at 23 each one goes up by 10</p>

<p>18…160
19…170
20…180
21…190
22…200
23…210</p>

<p>Bit of clarification needed I suppose.</p>

<p>@ankitp431, did you graph the equations during the test or afterwards?</p>

<p>Too bad we all have short memory and don’t remember the equation.</p>

<p>@jamdur, I suppose thats a easier way… easier than pluggin numbers…</p>

<p>@VouloirPouvoir (Post #353) and CompSciGeek (Post #355): Sent you both PMs</p>

<p>@CompSiGeek (Post #355)- Well you don’t have to plug in numbers. You could put the two sets into two lists in the graphing calculator (if you know how to do this) and find the linear regression equation (which is a function) and then plug in 21 in the function to find the answer.</p>

<p>But yeah jamdur’s method is faster and smarter lol.</p>

<p>^Ok i didnt mean plug in numbers I mean put in numbers to the lists</p>

<p>Also, do any of you remember question 46, 48, and 49?</p>

<p>@Compsci, I graphed them immediately, and kept on getting (0.6666666,0.000000001) as the intersection point.</p>

<p>@ankitp43l</p>

<p>Hm… I graphed it and there were no intersections… are you graphing the 2 new equations? I forgot what they were lemme edit this later.</p>

<p>|3x-2| = -|x+21|</p>

<p>I didnt find the intersection, i merely looked at the graph and saw that they didnt touch… It makes sense because both have no vertical transformations and different horizontal shifts and the 2nd is reflected.</p>

<p>What 2 new equations?</p>