<p>Hey people.. I don't know what's wrong, but I can't solve this one Math ex..</p>
<p>If w, x, y, and z are positive integers and have an average (arithmetic mean) equal to 150, which of the following CANNOT be a value of w, x, y, or z?
a)599
b)597
c)1
d)2
e)598</p>
<p>It seems simple but I dunno..
The answer, btw, is E.. But can u explain?? </p>
<p>Thanks!</p>
<p>Another one:
Two dice are thrown. What is the probability that their sum will be a prime number?
a)7/12
b)1/4
c)5/12
d)7/18
e)1/3</p>
<p>The answer is C…
Again… explanation needed :D</p>
<p>I’m not too sure, but I think that A should be correct as well…because if you multiply 150*4 to find the total value of w+x+y+z, you get 600. That means that if w, x, y, or z is equal to 598, then the other three must add up to 2. Since w, x, y, and z can only be positive integers, three of them cannot add up to 2. The same logic works to find that A should be correct also…</p>
<p>For the second one, the possible sums of the two dice are the integers from 2-12. Out of these integers, 2, 3, 5, 7, and 11 are prime. First you can calculate the number of possibilities of the sums by using the counting principle (I think that’s what it’s called) to get 6*6 = 36 total possibilities. Then you can figure out the number of ways to get each of the prime numbers. There is 1 way to sum to 2, 2 ways to sum to 3, 4 ways to sum to 5, 6 ways to sum to 7, and 2 ways to sum to 11, giving a grand total of 15 ways to sum to a prime number. Putting this over the total number of possibilities, we get 15/36=5/12.</p>
<p>These do NOT look like SAT questions. On the SAT answer choices are always given in increasing or decreasing order. The answer choices in these problems are all over the place. I would not use this source for SAT practice. You cannot practice SAT strategies if the problems are written incorrectly.</p>
<p>@Orchid</p>
<p>Yes, it’s called the counting principle, and it looks like you are correct about the flaw in the first problem.</p>
<p>Aside from the answers not being in numerical order (I usually don’t care much about that), both A and E are correct answers. You should look out for clear mistakes like those – I agree with DrSteve, I would refrain from using that test preparation source.</p>
<p>thanks everyone! That was my mistake in the first one too actually… I chose A. This is from testbeast.com which actually someone recommended over here 
… </p>
<p>Now I get the 2nd question @Orchid… Thanks! :D</p>
<p>Testbeast doesn’t look professional at all.
I’d refrain from using it.</p>
<p>what do you suggest then?</p>
<p>
</p>
<p>Well, now you know why some of us have warned everyone about the value of the synthetic tests. And, whenever you see a recommendation for some obscure outfit, you can bet your lunch money that the recommender was … someone with a vested interest. </p>
<p>When it comes to tests, stick to tests released by the College Board. Search past discussions about blue book, red book, QAs, online course, etc. </p>
<p>You should find more questions that are ever needed. And that means no reason to waste your time with garbage such as the obscure testbeat or the equally poor and misleading tests produced by PR, Kaplan, and the like.</p>
<p>oohhkay… Thanks… Barron’s on ur blacklist too? Just btw…</p>
<p>2200andbeyondXD,</p>
<p>I will second what xiggi and others are saying, stick with official SAT questions. Here is another reason: many SAT questions are repeats of what has been tested in the prior administrations of the test. Here is an example from the recent October 2012 SAT (Section 9, Q13):</p>
<p>“Company X packages cookies in boxes, targeting the weight of a box of cookies to be 500 grams. Any box of cookies that is within 15 grams of the target weight is acceptable. Which of the following represents all possible acceptable values of the weight, w, in grams, of a box of cookies?”</p>
<p>Answer: |w - 500| ≤ 15</p>
<p>You will see how similar it is to this question from Official SAT Study Guide 2nd Edition(TEST 5 SECTION 8 QUESTION 9):</p>
<p>“A regulation for riding a certain amusement park ride requires that a child be between 30 inches and 50 inches tall. Which of the following inequalities can be used to determine whether or not the child’s height H satisfies the regulation for this ride?”</p>
<p>Answer: |h - 40| < 10 </p>
<p>In fact, about 30% of the questions in the October SAT 2012 were more or less repeats or slight alterations of past questions. </p>
<p>Other than that ETS does a pretty good job of writing SAT questions. I know no one likes them but they are very thorough and professional when it comes to writing these questions. Here is why:</p>
<p>1) There is a group of very smart people who write and parse through these questions carefully, as opposed to random SAT sites that outsource questions to god knows who and where.
2) The questions are written very carefully and the language is very precise.
3) Each question has been pretested as part of the experimental section, thus eliminating questions that have any ambiguity. </p>
<p>Below is part of an answer on Quora from someone who worked for ETS writing multiple choice questions.
"However, to ETS’s credit, the tests are RIGOROUSLY tested.
ETS employs squadrons of statisticians. Every question is tested before being used, via the “experimental” section. This means that every scared test-taker is a guinea pig, doing work for which they receive no credit or compensation. But again, how else could ETS get real data to determine if a question is fair? And if a question has unusual results – way more whites, or men, get it right, for example – then they change or discard the question, even if it seems otherwise valid.</p>
<p>So, IMO, rant all you want about standardized testing, but ETS is actually doing a fair job of creating an unfair test."</p>
<p>Here is the complete link: <a href=“https://www.quora.com/Standardized-Tests/What-are-some-evil-or-unsavory-decisions-made-by-the-ETS-and-College-Board[/url]”>https://www.quora.com/Standardized-Tests/What-are-some-evil-or-unsavory-decisions-made-by-the-ETS-and-College-Board</a></p>