<p>You could do that…you want to cover the 15x24 area using 3x3 squares, so you need 40 of them. The 3x3 square is comprised of 5 tiles, so you need 40*5 = 200 tiles.</p>
<p>Thanks for the quick response rspence. That makes more sense.</p>
<p>In triangle ABC, if AB = 1 and BC = 100, which of the following must be true about the angles?
(a) The measure of angle A is greatest
(b) The measure of angle B is greatest
(c) The measure of angle A and angle B are equal
(d) The measure of angle C is greatest
(e) The measure of angle C is least. </p>
<p>First of all, how do you approach this question? I remembered that two sides must be greater than the the third and that angles correlate with side length but that didn’t help. After I got this problem wrong, I went back and saw that the answer was E, but I then didn’t understand how you would differentiate between that and C.</p>
<p>In 1954 the record time for running a mile was 4 minutes, and by 1975 the record had fallen to 3 minutes and 50 seconds. If the record had fallen at a constant rate during that time and continued to do so, in what year can it be expected that the record time for running a mile will be 3 and 1/2 minutes? </p>
<p>I tried doing slope formula for this one and got the wrong answer.</p>
<p>Answer was 2017</p>
<p>You don’t need any kind of slope formula for that problem, just think about it logically.</p>
<p>It took 21 years for the record to go down by 10 seconds, and that rate is staying constant. It asks when it will be 3 min 30 sec so the record must go down by 20 more seconds, which will take 42 years. </p>
<p>1975 + 42 = 2017</p>
<p>1954: 4 min
1975: 3 min 50 s
1996: 3 min 40 s
2017: 3 min 30 s (obtained by adding increments of 21).</p>
<p>Thanks. What about the triangle question (post 183)? How would I be able to tell whether its c or e? Is it safe to assume the triangle is isosceles?</p>
<p>The triangle does not have to be isosceles, but it doesn’t matter. Draw a quick picture and you wil see that the length of the third side has to be more than 99 abd less than 101 – but MUCH more than 1. In other words, AB is by far the smallest side so the angle across from it – angle C – must be the smallest angle.</p>
<p>This is actually a nice question. If it isn’t from an SAT, it still does a good job of testing two triangle concepts that show up on the SAT without going into material that doesn’t show up on the SAT. Where is it from?</p>
<p>The PSAT practice test 2010</p>
<p>Another question from the same source: On the number line above, the coordinates of two points are shown. If the distance between the points is 2, what is the value of x?
I’ll try my best to reproduce the number line with + representing a point.</p>
<ul>
<li>+ +<br>
.03x .04x</li>
</ul>
<p>(that didn’t work well, .03 is under the first point and .04 is under the third point)</p>
<p>Can someone explain the logical means of doing this question? I used the slope formula: (2-0)/ (0.04x - 0.03x) and obtained 200x. But then I just skipped the question because I didn’t know what to do with the 200x. Answer was 200.</p>
<p>And this question:
<a href=“http://i46.■■■■■■■.com/2cny5px.jpg[/IMG]”>http://i46.■■■■■■■.com/2cny5px.jpg
![http://i46.■■■■■■■.com/2cny5px.jpg[/IMG]](http://i46.tinypic.com/2cny5px.jpg%5B/IMG%5D){kind=link}
</a></p>
<p>I tried intercept form, standard form, and using shifts to make an equation, but I can’t come up with the right answer mathematically. I could look at the graph and determine the answer to be 1.5, but how would you know in this case and other cases that it’s not 1.53, 1.49, 1.4, or 1.6? Thus I tried used equations to find the answer.</p>
<p>Right answer is 1.5.</p>
<p>@arooj1a2b3c
.04x – .03x= 2 (-- represents subtracted by)
This gives you .01x=2
x=200</p>
<p>Just like if you had 10 and 5 on a number line. To find the distance between them you would subtract 5 from 10.</p>
<p>@arooj1a2b3c Where did you get the 2010 Practice test PSAT?
for the graph question: The maximum value of the quadratic graph is at the vertex. The vertex is located on the axis of symmetry which is halfway between 5 and -2. Use the midpoint formula to find the x value of the axis of symmetry. (5+ -2)/2 = 1.5</p>
<p>[Test</a> Preparation | The Geneva School](<a href=“http://www.genevaschool.org/upper-school/college-counseling/test-prep]Test”>http://www.genevaschool.org/upper-school/college-counseling/test-prep)</p>
<p>It has the 2010 and 2011 psat practice tests as a pdf if you scroll down a bit. I used to have the actual 2011 practice test booklet from taking the psat as a sophomore but I lost it.</p>
<ol>
<li>For how many two-digit positive numbers will tripling
the tens digit give us a two-digit number that is
triple the original number?
(A) None
(B) One
(C) Two
(D) Three
(E) Four</li>
</ol>
<p>i dont get it xD</p>
<p>@ elmarcom</p>
<p>Since you’re tripling the tens digit, this implies that the ones digit must be zero, b/c otherwise if you triple the tens, it can never be the number’s triple (i.e 11*3 DNE 31, 22 * 3 DNE 62), </p>
<p>Thus the answer is 3 or D, 10*3 = 30, 20 * 3 = 60, 30 * 3 = 90</p>
<p>Guys. here’s a math problem from one of the Khan Academy videos (problem 65 in this video: [Algebra</a> II: Functions, Combinatorics - YouTube](<a href=“Algebra II: Functions, Combinatorics - YouTube”>Algebra II: Functions, Combinatorics - YouTube))</p>
<p>Teresa and Julia are among 10 students who have applied for a trip to Washington, D.C. Two students from the group will be selected at random for the trip. What is the probability that Teresa and Julia will be the 2 students selected?</p>
<p>Answer (according to Sal): 1/45</p>
<p>Now, according to how Sal did it, he assumed that the two girls are selected one at a time. If that is the case, then the answer would be 1/45, but I understood it, as many other people did, that they were both chosen at one time, and that there was no order thing. If that’s the case, the answer should be 1/90. How did Sal know which way to go? Am I missing something or is the question wrong or what? Thanks!! :)</p>
<p>One nice (or not nice, depending on your feelings) thing about probability and combinatorics is that many problems have multiple ways you can approach them.</p>
<p>Thinking of picking one kid at a time:</p>
<p>The first pick has to be one of the two girls. Probability = 2/10
The next pick has to be the remaining girs. Probability = 1/9</p>
<p>(2/10) x (1/9) = 2/90 = 1/45</p>
<p>Thinking of it has making both picks simultaneously:</p>
<p>There are 10C2 = 10 x 9 /2 = 45 ways to pick 2 people from 10. Of those 45 ways, only one combination consists of the two Julia and Teresa. So probability = 1/45</p>
<p>Same answer… :)</p>
<p>The total number of choices of 2 students is 10C2 = 45. There is only one “success” (A success being that Teresa and Julia are selected). So the answer is 1/45.</p>
<p>I used a combination here because we are just choosing 2 students from a group - we are NOT arranging them.</p>
<p>I think you made the mistake of finding the permuation 10P2 = 90. In this problem there is no permutation. {Teresa, Julia} is the same as {Julia, Teresa}.</p>
<p>In a tournament, each of the 6 participants played 2 matches against each of the other participants. What was the total number of matches played during the tournament?</p>
<p>The answer is 30, but how is this a permutation? I can do 6P2 on my calculator and get 30. I thought it wouldn’t matter whether participant a played against participant b or if participant b played against participant a.</p>