Search found 22 matches
I haven't seen the original source on this one, but it sounds a lot like an "invented symbol function" problem, which is that often-confusing question type where the GMAT will give you something like the following: if A :) B = some function, what is 5 :) 3 ? You guys have probably seen the...
- by stephen@knewton
Tue Jun 15, 2010 12:51 pm- Forum: Problem Solving
- Topic: solution plz..
- Replies: 7
- Views: 1868
Hi Martin (and to the OP), I'm sorry for not giving a more detailed explanation of why (C) isn't correct. The problem with that answer choice is actually rather simple, but for that reason it CAN be easy to overlook, so I certainly understand the confusion. The problem is that nothing in the prompt ...
- by stephen@knewton
Fri Jun 04, 2010 3:06 am- Forum: Critical Reasoning
- Topic: Political theorist_LSAT CR.
- Replies: 5
- Views: 2637
As both an LSAT and GMAT teacher, let me see if I can use this as an excuse to shed a bit of light ... and by light, of course I mean formal logic! :) This question contains CONDITIONAL statements, and such questions are best attacked by "translating" the English sentences into formal logi...
- by stephen@knewton
Thu Jun 03, 2010 1:34 pm- Forum: Critical Reasoning
- Topic: Political theorist_LSAT CR.
- Replies: 5
- Views: 2637
Crasher, The key to your question from GMATprep is to recognize that because your variable appears within an exponent on base 2, you need to "create" a 3 somewhere on the left side of the equation. That way, you'll be able to cancel the 3s and compare the exponents of like bases. You must ...
- by stephen@knewton
Mon May 24, 2010 1:08 pm- Forum: Problem Solving
- Topic: If 3^6x = 8,100, what is the value of [(3^x – 1)]^3 ?
- Replies: 11
- Views: 11894
Hi Bupbebeo, You're on the right track in trying the negation test, and you've stated its purpose perfectly! Let me see if I can help you to make it work. Let's take a careful look at the negations of (C) and (D) and their impact on the conclusion. To do that, let's first VERY carefully identify the...
- by stephen@knewton
Sat May 22, 2010 4:44 am- Forum: Critical Reasoning
- Topic: Research shows
- Replies: 4
- Views: 1519
Great work from both responders, but let me offer a quick endorsement for the strategy proposed by kikor65! Whenever you are dealing with a percentage problem, plugging in 100 provides a quick and fool-proof way to handle the calculations. The algebraic method always WORKS, but the more complex the ...
- by stephen@knewton
Thu May 20, 2010 1:11 pm- Forum: Problem Solving
- Topic: How much Z?
- Replies: 5
- Views: 1203
You're very welcome! To answer a follow-up question that's been raised, "decreased probability" would indeed also be a good alternative, if it were among the answer choices ... ... HOWEVER ... this might be a good excuse to share some cautionary test-taking advice for SC: "pre-phrasin...
- by stephen@knewton
Tue May 18, 2010 4:48 am- Forum: Sentence Correction
- Topic: parallelism
- Replies: 9
- Views: 1701
This one throws a very interesting curve ball. As varying interpretations among the previous posts suggest, there actually IS some ambiguity about what must be parallel. Without the answer choices to guide us, we're not sure if we're looking at: "... could lead ... and verb ..." or "....
- by stephen@knewton
Mon May 17, 2010 2:33 pm- Forum: Sentence Correction
- Topic: parallelism
- Replies: 9
- Views: 1701
Just a quick test tip on this one, folks. A problem like this demonstrates the importance of being able to quickly "Reverse FOIL" a quadratic equation. This is a great technique for anybody that wants to solve this without introducing new variables. The technique, in brief, is as follows. ...
- by stephen@knewton
Wed May 12, 2010 6:04 am- Forum: Problem Solving
- Topic: quadratics question
- Replies: 5
- Views: 1306
Some great questions raised in this thread. I think it will help to recall two things about a "conclusion" question, which is very similar to an inference question. First, remember what our task is: we must pick and answer choice that MUST be true based upon the evidence that's presented i...
- by stephen@knewton
Tue May 04, 2010 4:37 am- Forum: Critical Reasoning
- Topic: The red-eyed cowbird
- Replies: 7
- Views: 1880
Hi TTD, As both a GMAT teacher and someone who took the official test after a 12-year hiatus from mathematics, I'd like to commend your willingness to ask for help on a problem that MANY students face in frustrated silence. Make no mistake, reducing "unforced errors" is one of the most cha...
- by stephen@knewton
Thu Apr 22, 2010 6:43 am- Forum: GMAT Math
- Topic: Calculation / Arithmetic Errors
- Replies: 2
- Views: 1390
As both a GMAT and LSAT teacher, I love seeing questions like this on BTG! :) The LSAT has a much greater focus on formal logic than the GMAT does, but GMAT students can definitely benefit from learning to think that way. So let's use formal logic to unpack this question. You'll be surprised how pow...
- by stephen@knewton
Mon Apr 19, 2010 4:45 pm- Forum: Critical Reasoning
- Topic: West Side School, LSAT CR
- Replies: 6
- Views: 2940
Vivek, Thanks for posting this. Relevance questions can be very tricky. As with any CR question, I recommend unpacking the stimulus before you do anything else. Once you know how the argument is formed, you'll be much better able to see what is relevant to it. Evidence: 1) Rare F killed trees --> un...
- by stephen@knewton
Thu Apr 15, 2010 9:50 am- Forum: Critical Reasoning
- Topic: cacao trees
- Replies: 5
- Views: 2496
Nope, you've done a good job! The mean will ALWAYS be (40+x)/5 The median can have three values: 8 for all X<=8 X for all 8<X<12 12 for all X>=12 (For the sake of completeness, I'll point out that even for X=8 or X=12 the set becomes {4, 8, 8, 12, 16} or {4, 8, 12, 12, 16} respectively, and thus the...
- by stephen@knewton
Tue Apr 13, 2010 12:07 pm- Forum: Problem Solving
- Topic: mean median
- Replies: 11
- Views: 4288
... and since I also teach sentence correction, I should correct my last paragraph. The form DESCRIBES.
- by stephen@knewton
Thu Apr 08, 2010 5:03 am- Forum: Problem Solving
- Topic: Inequalities trick
- Replies: 11
- Views: 2867