OFFICIAL AP Calculus BC 2012 Test Thread

Test Preparation AP Mathematics & Computer Science
281

<p>Made a correction on the speed- redoing it shows that it’s .785 not .575. Also added alternate explanation on 5b. These should be the right answers, my calculus teacher, those teachers on the websites, and I got the same key.</p>

<p>1-
a) 1.017 degrees F/minute, the temperature of the water is changing at a rate of approximately 1.017 degrees per minute at time 12.
b) 16 degrees F- the water rose 16 degrees from 0 to 20 minutes
c) 60.79 degrees F, understated, the largest temperature is excluded in the left hand approximation and the temperature is strictly increasing over time.
d) 73.043 degrees F</p>

<p>2-
a) It’s going to the right because dx/dt is positive, slope= 3.055
b) 1.253
c) speed= .785, acceleration vector= <-.0411, .989>
d) .651</p>

<p>3-
a) -1/4, (pi-3)/2
b) 2, 1
c) at -1 and 1. -1 is a maximum because the sign chart shows it going from + to -, but 1 is nothing.
d) at -2, 0, 1. These are the points where f’ changes sign.</p>

<p>4-
a) 18.2
b) 19.6
c) 19
d) 19.8</p>

<p>5-
a) It gains weight faster at 40 because plugging in 40 to the rate given compared to 70 results in a greater rate.
b) db/dt= -1/25[100-B]. Using sign chart, 0= -, 200= +, so 100 is a point of inflection. The graph doesn’t show it. OR The graph must be concave down over the interval from 0-100, which doesn’t show in the graph.
c) y= 100-80e^(-1/5t)</p>

<p>6-
a) -1<=x<=1
b) 1/224 is the first neglected term and must be greater than the error according to ASRT. 1/224 is less than 1/200 so the approximation error is less than 1/200.
c) 1/3-3x^2/5+5x^4/7…[(-1)^n(2n+1)x^2n]/[2n+3]</p>

282

<p>@nostalgicwisdom how is the speed .785, i got .575 and I keep redoing it and getting .575, am i missing something?</p>

283

<p>speed= sqrt( (dx/dt)^2+ (dy/dt)^2)</p>

<p>dx/dt at 4= root(6)/e^4= .04486
dy/dt at 4= sin(4)^2= .57275</p>

<p>sqrt(.04486^2+.57275^2)= .575</p>

<p>Sorry, in my redo I forgot that I had to square the values of dx/dt and dy/dt, so it IS .575.</p>

284

<p>no problem, thanks for confirming and thanks for posting your solutions, they have been really helpful</p>

285

<p>Here are my solutions scanned so you can see the step by step work.</p>

<p><a href=“http://s7.postimage.org/nntb367ne/Question_1.jpg[/url]”>http://s7.postimage.org/nntb367ne/Question_1.jpg&lt;/a&gt;
<a href=“http://s17.postimage.org/u365sfnbj/Question_2.jpg[/url]”>http://s17.postimage.org/u365sfnbj/Question_2.jpg&lt;/a&gt;
<a href=“http://s17.postimage.org/racy8emz3/Question_3.jpg[/url]”>http://s17.postimage.org/racy8emz3/Question_3.jpg&lt;/a&gt;
<a href=“http://s17.postimage.org/m2wghovrj/Question_4.jpg[/url]”>http://s17.postimage.org/m2wghovrj/Question_4.jpg&lt;/a&gt;
<a href=“http://s17.postimage.org/8ai1m24zz/Question_5.jpg[/url]”>http://s17.postimage.org/8ai1m24zz/Question_5.jpg&lt;/a&gt;
<a href=“http://s17.postimage.org/kqerfsybz/Question_6.jpg[/url]”>http://s17.postimage.org/kqerfsybz/Question_6.jpg&lt;/a&gt;&lt;/p&gt;

286

<p>Does anybody remember a single area question on the MC, besides the polar one. Also, were there any questions where an integral had to be split up due to the function changing signs?</p>

287

<p>How many points would I miss for only getting 2 out of the 3 inflection points right? Sorry, the only reason I’m asking is because I bombed the no calculator MC and need every point I can get on the FR haha.</p>

288

<p>would 74/108 MC cut it for a 5 for this relatively easy test?</p>

289

<p>^would like to know this too.</p>