Official AP Statistics Thread 2012

Test Preparation AP Mathematics & Computer Science
181

<p>So now that we’re free to discuss can someone explain 6 B) and C) please? Because I remember on the exam I got that Rania’s SD was higher than Peter’s but other people have been saying the opposite.</p>

182

<p>For number 4 could you say that the data would not work because of a bias- the survey was taken using the phone so not all the population had a equal chance of being surveyed?</p>

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<p>For Peter:
= (4.13)/(sqrt(100) = 4.13/10 = 0.413</p>

<p>For Raina:
SD for females = (1.80)/(sqrt(60)) = 0.232
SD for males = (2.22)/(sqrt(40)) = 0.351</p>

<p>Overall SD = sqrt[(0.6^2)(0.232^2) + (0.4^2)(0.351^2)]
= 0.198</p>

184

<p>Seems like FRQ’s have been released. For Raina’s data, </p>

<p>The standard deviation of .6X_female is .6(1.80/sqrt(60)) = 0.139427</p>

<p>The standard deviation of .4X_male is .4(2.22/sqrt(40)) = 0.140405</p>

<p>Therefore the standard deviation of .6X<em>female + .4X</em>male is sqrt(0.139427^2 + 0.140405^2) = .197872.</p>

<p>Darn, I think I got .28 something on #6 part C (I don’t think I added the standard deviations). Idk what I did…had like 2 minutes left before I realized I screwed up #6.</p>

185

<p>^ That’s what I got.</p>

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<p>Well, just realized that</p>

<p>sqrt((0.6)(0.232^2) + (0.4)(0.351^2)) = .28561… (similar to JoeBloggsTroll’s post but I didn’t square the .6, .4)</p>

<p>That’s probably what I did wrong…oh well. I’m pretty sure I nailed #1-5 and #6a, b.</p>

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<p>Is that what you guys put for b and c on #1? : <a href=“http://i45.■■■■■■■.com/2cr1wlc.jpg[/url]”>http://i45.■■■■■■■.com/2cr1wlc.jpg&lt;/a&gt;&lt;/p&gt;

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<p>@JoeBloggsTroll yep.</p>

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<p>why isn’t it .285? i did:</p>

<p>sqrt((0.6)((1.8^2)/60))+(0.4)((2.22^2)/40)))=.285…</p>

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<p>classof1313, See this: [TinyGrab</a> - Simple. Screenshot. Sharing.](<a href=“http://grab.by/dH9o]TinyGrab”>http://grab.by/dH9o)</p>

<p>The two calculations at the bottom show what you did vs. what was correct — I almost made the same mistake but then remembered that σ²=b²σ², where b is the scalar.</p>

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<p>I’m so excited to find out I did 6c right. Pure joy.</p>

192

<p>So I got 6C wrong, oh well. I’m pretty sure I got every other FRQ right. Does anyone have a score calculator so I can see how many MC questions I could miss and still get a 5?</p>

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<p>

It’s the standard deviations that is being affected by the multiplier. Thus, when you square the standard deviation, the multiplier of the standard deviation is also squared.</p>

<p>think of it like</p>

<p>new standard dev = b(standard dev)
When you square it…</p>

<p>variance = (new standard dev)^2 = b^2(standard dev)^2</p>

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<p><a href=“http://roughlynormal.files.■■■■■■■■■■■■■/2012/05/possible-solutions-2012-fr-questions3.pdf[/url]”>http://roughlynormal.files.■■■■■■■■■■■■■/2012/05/possible-solutions-2012-fr-questions3.pdf&lt;/a&gt;&lt;/p&gt;

195

<p>Wait, aren’t there two forms for APs? I’m an international, so wouldn’t I get a Form B? I seem to have gotten the same FRQs as everyone else on here.</p>

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<p>I got a different form of the free response, which I guess is normal as different forms are distributed. But why has College Board only released one form, the one everyone else on here is discussing? It’s making me paranoid…</p>

<p>But anyway, that form was difficult. The focus of question six was something I swear was never discussed in class nor my review book, though the rest were okay.</p>

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<p>@crush I got a different form for the AP calculus test AB which was one of the beginning AP tests and college board hasn’t released that one. I think its something new this year where certain people get picked to have a different form for the free response and they might not never release those different forms.</p>

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<p>What kinds of questions did you get, crushtheinfamous?</p>

<p>Just out of curiosity, do the people who take the late exam get Form B, since it wasn’t released, or could they still get the one that CollegeBoard posted?</p>

199

<p>I want to ask you guys a question, especially for those who have self-learned AP statistic.
As I was told that AP statistic is kind of an easy course/exam. For a student who has finished advanced algebra, how many hours are needed to self-learn AP statistic?
I just want to get a rough idea, like 50 - 100 hours? 100- 150 hours? 200 hours? 300 hours? 400+ hours?</p>

<p>Any response will be greatly appreciated!</p>

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<p>^My friend who is really good at math(has studied the entire undergraduate math cirriculum by 11th grade) was able to study it for around 2-4 days before the exam, and he got a 5 without knowing how to do hypothesis testing</p>