PSAT Clock Problem

Test Preparation SAT Preparation
1

<p>I initially put down A, which was the correct answer, but then I switched it to C. </p>

<p>Can someone please explain why the answer is A?</p>

<p>Untitled</a> - Minus.com</p>

<p>This is what I did:</p>

<p>4:00 is 11 hours away from 5:00. 4:00 can only have multiples of 11 - e.g. 11 hours, 22 hours, 121 hours. </p>

<p>If 4:00 is the 121st hour, then 8:00 must be the 125th hours.</p>

<p>What's wrong with my reasoning? I'm not seeing it :mad:.</p>

2

<p>every 12 hours the clock is going to be right at 5:00 again… and you know that it will go around 12 hours 10 times (120 hours), and then go around for 5 more hours. So just count 5 hours past 5:00 and you get 10:00 (answer A).</p>

3

<p>Thanks, but I don’t see why my method can’t work. </p>

<p>And here’s another question. </p>

<p>[12</a> - Minus.com](<a href=“http://min.us/m0FUZ43Cf]12”>http://min.us/m0FUZ43Cf)</p>

4

<p>@IceQube- your method doesn’t work because you assume that after every 11 hours that passes, the clock is at 4:00 again. The FIRST time it goes around 11 hours, it will be at 4, but the second time it will stop at 3.</p>

<p>for your other problem I think it’s B. if the value of the number is always less than -4 or greater than 4, that means the number’s absolute value is always greater than 4 which makes II correct. I is correct because when you square a real number, the result is always positive. III is incorrect because if you cube a negative real number, the result will be negative, and a negative number cannot be >4.</p>

5

<p>Thank you for your explanation of the first problem :)! Here is the fixed link to the second problem: <a href=“http://k.minus.com/jDek95h6Hlxhg.png[/url]”>http://k.minus.com/jDek95h6Hlxhg.png&lt;/a&gt;&lt;/p&gt;

<p>About the second problem: the wording threw me off. If x was > 4, then x^3 is greater than 4. The problem states that if x < -4 OR x >4, then which MUST be true … </p>

<p>Did you find the wording confusing? Does anyone else find the wording of the second problem problematic?</p>

6

<p>yeah they DEFINITELY should have used “and” instead of “or”. are these official questions btw?</p>

7

<p>^Yes, those are from the 2004 PSAT practice booklet. The questions were the first of their kind, and they were never officially administered.</p>

8

<p>But they could not use “and”! If it said: x>4 AND x < -4 … that would cause a rift in the space-time continuum.</p>

9

<p>^Good point. But did you find the wording confusing?</p>

10

<p>The wording is correct.</p>

11

<p>The wording is correct – the problem is lazy habits we form in school math (students and teachers both).</p>

<p>Consider : (x-2)(x-3)=0.</p>

<p>We often say that answers are x= 2 and x=3. We MEAN x=2 OR x=3…obviously it can’t be both at once. But it would be correct (though longer) to say that the solution set cotains two elements and that those two elements are x=2 and x=3. And being lazy, we say “x=2 and x=3”, “knowing” what we all mean.</p>

<p>Bottom line: the SAT is always worded with meticulous care. Trust the words. And to conquor the math, you have to learn to love fine distinctions in reading!</p>

12

<p>Anybody will post the damn answer here. I think it is ‘B’ but want a confirmation.</p>

13

<p>9 is C. This is the clock problem.
15 is B.</p>

14

<p>

</p>

<p>I think you meant A.</p>

15

<p>I say B for the second problem and here is my reasoning:</p>

<p>x < -4 , choose -5
x > 4, choose 5</p>

<p>x^2 > 4 = (-5)^2 = 25, (5)^2 = 25 WORKS FOR BOTH</p>

<p>l x l > 4 = l -5 l = 5 > 4, l 5 l =5 > 4 WORKS FOR BOTH</p>

<p>x^3 > 4 = (-5)^3 = -125 > 4 NO, but (5)^3 > 4 = 125 > 4 YES, but since one part of this statement is false, the entire thing must be false.</p>

<p>therefore, only I and II can be correct.</p>

16

<p>Oops, I did mean A :eek:.</p>