Math questions from any Manhattan Prep GMAT Computer Adaptive Test.
viksnme
 
 

Negative x ? Online Test DS #5

by viksnme Fri Apr 25, 2008 2:40 am

Is x a negative number?

(1) x^2 (squared) is a positive number.

(2) x · |y| is not a positive number.

Hi Guys,
statement 1 tells us that x cannot be 0. But it can be +ve or -ve hence Inusfficient.
statement 2 tells us that x cannot be +ve. But it can be -ve or it can be 0. Hence Insufficient.

But if we combine 1 and 2, surely, we can rule out both 0 and +ve values but a negative x is common to both 1 and 2; x should be negative. Should the answer hence be C?
UPA
 
 

Re: Negative x ? Online Test DS #5

by UPA Sun Apr 27, 2008 3:35 am

viksnme Wrote:Is x a negative number?

(1) x^2 (squared) is a positive number.

(2) x · |y| is not a positive number.

Hi Guys,
statement 1 tells us that x cannot be 0. But it can be +ve or -ve hence Inusfficient.
statement 2 tells us that x cannot be +ve. But it can be -ve or it can be 0. Hence Insufficient.

But if we combine 1 and 2, surely, we can rule out both 0 and +ve values but a negative x is common to both 1 and 2; x should be negative. Should the answer hence be C?


nothing wrong seems to me.
UPA
Captain
 
 

by Captain Tue Apr 29, 2008 8:13 am

What happens if x = 2 and y = 0??
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Re: Negative x ? Online Test DS #5

by RonPurewal Wed Apr 30, 2008 5:05 am

viksnme Wrote:But if we combine 1 and 2, surely, we can rule out both 0 and +ve values


make sure you track the status of each variable separately.

you ruled out 0 for x, but not for y. therefore, as captain said in the post above this one, x can still be positive, if y is 0.

tricky tricky
viksnme
 
 

Negative x ? Online Test DS #5

by viksnme Sat May 03, 2008 8:27 pm

Got it guys (Captain and Ron), thanks. It is so easy to miss a condition. May be writing down will avoid this.
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by StaceyKoprince Thu May 08, 2008 1:28 am

Write EVERYTHING down. Your pen should be moving constantly - I will literally write down 2+2. It doesn't take me any more time to write while I think and I can avoid careless mistakes and/or overlooking important little details if I make it a habit to write down absolutely everything.
Stacey Koprince
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Director, Content & Curriculum
ManhattanPrep
viksnme
 
 

thanks Stacey

by viksnme Sat May 10, 2008 9:59 am

skoprince Wrote:Write EVERYTHING down. Your pen should be moving constantly - I will literally write down 2+2. It doesn't take me any more time to write while I think and I can avoid careless mistakes and/or overlooking important little details if I make it a habit to write down absolutely everything.


Many thanks Stacey. This is a gem of an advice and I have already started following it. I can see the difference it makes. Your suggestion has just re-confirmed that I must carry on doing that. You are the best.
I dont take notes while doing CR and SC though. Do you suggest it is worthwhile? I am comfortable with SC now but for CR I have still some way to go.
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by RonPurewal Mon May 26, 2008 10:11 pm

skoprince Wrote:Write EVERYTHING down. Your pen should be moving constantly - I will literally write down 2+2. It doesn't take me any more time to write while I think and I can avoid careless mistakes and/or overlooking important little details if I make it a habit to write down absolutely everything.


yeah

i swear, the last time i forgot to write 'breathe in, breathe out' on the top of the paper, i almost choked to death. wait what?
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Re: thanks Stacey

by RonPurewal Mon May 26, 2008 10:13 pm

viksnme Wrote:I dont take notes while doing CR and SC though. Do you suggest it is worthwhile? I am comfortable with SC now but for CR I have still some way to go.


you don't have time to take notes on s.c., except for making a PROCESS OF ELIMINATION CHART (nothing fancy - just a chart with ABCDE's that you cross off when you have eliminated the answer choices). that's more essential than you might think - it's much easier than you think to get lost, and forget which answer choices you've eliminated, on a s.c. problem with really really really long answer choices.

for c.r., i would suggest making a diagram for LONGER passages, and for ANY passage that you can't read right through and understand on your first pass through it. in other words, if you hesitate AT ALL while you read a passage, then you should immediately start making a diagram.
for shorter and/or easily understood passages, diagrams are largely unnecessary.
viksnme
 
 

Re: thanks Ron

by viksnme Sun Jun 29, 2008 6:56 am

Many thanks Ron for the suggestions. I shall try to follow them. Did not realise that you had replied to this post hence took longer to reply.
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by StaceyKoprince Wed Sep 03, 2008 7:04 pm

we're glad to help!
Stacey Koprince
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yousuf_azim
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Re: Negative x ? Online Test DS #5

by yousuf_azim Mon Aug 29, 2011 9:13 am

I think ans should be E.

BR
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Re: Negative x ? Online Test DS #5

by jnelson0612 Sat Oct 01, 2011 3:47 pm

mmrs151 Wrote:I think ans should be E.

BR


Tell us why. Did you test numbers? Did you determine what values are possible for each statement? Please share some of your reasoning.
Jamie Nelson
ManhattanGMAT Instructor