SAT II Math Questions!!!

Test Preparation SAT Subject Test Preparation
1

<p>1) If f(x)= (1/square root 2pi)e^(-xsquared/2), then for which of the following calues of x does f(x) =.33?
A) .62
B) .71
C) 1.36
D) 3.93
E) 4.95</p>

<p>2) If x>0 and y>1, then log(x^2)y=
I. log(x)y^2
II. log(x)squarerooty
III. log(x) (y/2)
(all the x's in parantheses are bases for the logs)</p>

<p>3) What is the value of |6-3i|?</p>

<p>4) The men of a cetain restaurant lists 10 items in column A and 20 items in column B. A family plans to share 5 items from column A and 5 items from column B. If none of the items is found in both columns, then how many different combinations of itms could the family choose?</p>

<p>5) Seven blue marbles and six red marbles are held in a single container. Marbles are randomly selected one at a time and not returned to the container. If the first two marbles selected are both blue, what is the probablility that at least two red marbles will be chosen in the next three selections?</p>

2

<ol>
<li>A</li>
<li>III</li>
<li>?</li>
<li>10 x 9 x 8 x 7 x 6 x 20 x 19 x 18 x 17 x 16</li>
</ol>

3

<ol>
<li>can be solved easily by your calculator. Under the MATH option, choose “abs.”</li>
</ol>

<p>abs(6-3i)</p>

4

<p>Oh wait read three incorrectly, yeah, all you have to do is pull out a three and then simplify the expression by using its complex conjugate, yielding 3sqrt(5)</p>

5

<p>well, i tried the 10*9…thing, and its wrong, for some reason…and how did u get one and two?</p>

6

<p>Sorry, I misread your number 4 as well, it should be 10C5 x 20C5=3907008</p>

7

<p>wats 10c5, like the c? computation? and ur coreect on it, but no, its 19/33, no clue why</p>

8

<p>Here, I’ll try to explain all of the questions for you.</p>

<ol>
<li>Plug it into a calculator and you get 0.62.</li>
<li>III is the only correct answer as log(x^2) y= logy/logx^2=logy/2logx=log(x)y/2</li>
<li>Look at Allexas’s solution, it’s correct.</li>
<li>10c5 is a combination (check here to learn about them:[Combination</a> - Wikipedia, the free encyclopedia](<a href=“http://en.wikipedia.org/wiki/Combination]Combination”>Combination - Wikipedia))</li>
<li>The answer is 19/33, the only ways that you can have at least 2 R are (RRR), (RRB), (BRR), and (RBR). Add up the separate probabilities and you will get 19/33.</li>
</ol>

<p>Hope I made some sense =)</p>

9

<p>thank you so much, that helped alot</p>

10

<p>Glad I could help, let me know if you have more questions.</p>

11

<p>ok, so there’s this one i couldn’t post, but it goes like this…If f(x)=, where is the greatest integer less than or equal to x, which of the following is a graph of f(x/2)-1? and it just has 5 piecewise function graphs…i have no idea how to do it, but all go from bottom left to upper right…?</p>

12

<p>You are dealing with the floor function, which looks like: <a href=“http://www.mathwords.com/f/f_assets/floor_graph.gif[/url]”>http://www.mathwords.com/f/f_assets/floor_graph.gif&lt;/a&gt;&lt;/p&gt;

13

<p>ya, but how does the x/2 or -1 affect it?</p>

14

<p>Divide each piece by two and subtract one.</p>

15

<p>I still don’t quite get number 5.</p>

<p>As for number 3, imagine that instead of an X and Y axis, there is a Real number (the 6) and an Imaginary Axis (the -3i)</p>

<p>So absolute value is the distance from 0, so just use the distance formula with (radical [36+9] )</p>

<p>=)</p>

<p>Could someone try to explain 5 a little more? haha thank you!</p>

16

<p>i still dont get number three
…</p>

<p>abs (6-3i)</p>

<p>how the hey’ll do u take out a three and it becomes</p>

<p>3 square root of 5 or something like that</p>

<p>can someone explain it again plz?</p>

<p>thanks</p>

17

<p>5.

After 2 Bs are removed there remain 5 Bs and 6 Rs (11 altogether).
P(RRB) = (6/11)x(5/10)x(5/9) = 5/33
P(RBR) = (6/11)x(5/10)x(5/9) = 5/33
P(BRR) = (5/11)x(6/10)x(5/9) = 5/33
P(RRR) = (6/11)x(5/10)x(4/9) = 4/33</p>

<p>P(RRB) + P(RBR) + P(BRR) + P(RRR) = 19/33.</p>