Find all School-related info fast with the new School-Specific MBA Forum

It is currently 20 Oct 2014, 03:26

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Is M<0? (1) -M = |-M| (2) M^2 = 9

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
1 KUDOS received
SVP
SVP
avatar
Joined: 17 Feb 2010
Posts: 1560
Followers: 12

Kudos [?]: 223 [1] , given: 6

Is M<0? (1) -M = |-M| (2) M^2 = 9 [#permalink] New post 27 Aug 2010, 13:35
1
This post received
KUDOS
7
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  75% (hard)

Question Stats:

34% (01:34) correct 66% (00:32) wrong based on 222 sessions
Is M<0?

(1) -M = |-M|
(2) M^2 = 9

I got very confused with option 1 and took lot of time with this question. Can someone help me unedstand how I can solve such questions quickly.
[Reveal] Spoiler: OA

Last edited by Bunuel on 18 Sep 2012, 05:16, edited 1 time in total.
Edited the question.
Expert Post
15 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23330
Followers: 3599

Kudos [?]: 28589 [15] , given: 2803

Re: Is [m]M<0[/m]? [#permalink] New post 27 Aug 2010, 14:02
15
This post received
KUDOS
Expert's post
1
This post was
BOOKMARKED
seekmba wrote:
Is M<0?

1. -M = |-M|
2. M^2 = 9

I got very confused with option 1 and took lot of time with this question. Can someone help me unedstand how I can solve such questions quickly.


Is m<0?

(1) -m=|-m| --> first of all |-m|=|m|, (for example: |-3|=|3|=3), so we have -m=|m|, as RHS is absolute value which is always non-negative, then LHS, {-m} must also be non-negative --> -m\geq{0} --> m\leq{0}, so m could be either negative or zero. Not sufficient.

(2) m^2=9 --> m=3=positive or m=-3=negative. Not sufficient.

(1)+(2) Intersection of the values from (1) and (2) is m=-3=negative, hence answer to the question "is m<0" is YES. Sufficient.

Answer: C.

Hope it's clear.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

SVP
SVP
avatar
Joined: 17 Feb 2010
Posts: 1560
Followers: 12

Kudos [?]: 223 [0], given: 6

Re: Is [m]M<0[/m]? [#permalink] New post 28 Aug 2010, 06:24
Thanks so much Bunuel.
Intern
Intern
avatar
Joined: 23 Aug 2010
Posts: 5
Followers: 0

Kudos [?]: 0 [0], given: 30

Re: Is [m]M<0[/m]? [#permalink] New post 28 Aug 2010, 12:16
Bunuel ,i love youuuuuuuuuuuuuuuuuuuu!!!!!!!
CEO
CEO
User avatar
Status: Nothing comes easy: neither do I want.
Joined: 12 Oct 2009
Posts: 2794
Location: Malaysia
Concentration: Technology, Entrepreneurship
Schools: ISB '15 (M)
GMAT 1: 670 Q49 V31
GMAT 2: 710 Q50 V35
Followers: 181

Kudos [?]: 983 [0], given: 235

Reviews Badge
Re: Is [m]M<0[/m]? [#permalink] New post 28 Aug 2010, 12:45
very nicely explained by Bunnel.

The tricky part here was the consideration of zero.
While dealing with these type of DS questions always consider scenario of -ve, 0 ,and +ve numbers.
_________________

Fight for your dreams :For all those who fear from Verbal- lets give it a fight

Money Saved is the Money Earned :)

Jo Bole So Nihaal , Sat Shri Akaal

:thanks Support GMAT Club by putting a GMAT Club badge on your blog/Facebook :thanks

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Gmat test review :
670-to-710-a-long-journey-without-destination-still-happy-141642.html

Expert Post
Founder
Founder
User avatar
Affiliations: UA-1K, SPG-G, HH-D
Joined: 04 Dec 2002
Posts: 12332
Location: United States (WA)
GMAT 1: 750 Q49 V42
GPA: 3.5
WE: Information Technology (Hospitality and Tourism)
Followers: 2323

Kudos [?]: 9392 [0], given: 3696

GMAT ToolKit User Premium Member CAT Tests
Re: Is [m]M<0[/m]? [#permalink] New post 28 Aug 2010, 12:49
Expert's post
amlandutta007 wrote:
Bunuel ,i love youuuuuuuuuuuuuuuuuuuu!!!!!!!


It is not an uncommon reply to Bunuels posts :lol:

You can kindly give Bunuel Kudos (there is a button for that)

P.S. You can also "Follow" bunuel (you will get daily summaries of his posts) so you don't miss any wisdom. There is a follow button next to his name.
_________________

Founder of GMAT Club

Just starting out with GMAT? Start here... | Want to know your GMAT Score? Try GMAT Score Estimator
Need GMAT Book Recommendations? Best GMAT Books

Co-author of the GMAT Club tests

Have a blog? Feature it on GMAT Club!

Get the best GMAT Prep Resources with GMAT Club Premium Membership

CEO
CEO
User avatar
Status: Nothing comes easy: neither do I want.
Joined: 12 Oct 2009
Posts: 2794
Location: Malaysia
Concentration: Technology, Entrepreneurship
Schools: ISB '15 (M)
GMAT 1: 670 Q49 V31
GMAT 2: 710 Q50 V35
Followers: 181

Kudos [?]: 983 [0], given: 235

Reviews Badge
Re: Is [m]M<0[/m]? [#permalink] New post 28 Aug 2010, 13:00
I love the 'follow' feature. :cool

I remember you posted something on the top notification- all know how to lead, can you follow?.

I feel I m actually leading them by following what are they posting, though I m not the leader. A new way to look at the leadership.
_________________

Fight for your dreams :For all those who fear from Verbal- lets give it a fight

Money Saved is the Money Earned :)

Jo Bole So Nihaal , Sat Shri Akaal

:thanks Support GMAT Club by putting a GMAT Club badge on your blog/Facebook :thanks

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Gmat test review :
670-to-710-a-long-journey-without-destination-still-happy-141642.html

Senior Manager
Senior Manager
avatar
Joined: 18 Aug 2009
Posts: 437
Schools: UT at Austin, Indiana State University, UC at Berkeley
WE 1: 5.5
WE 2: 5.5
WE 3: 6.0
Followers: 6

Kudos [?]: 52 [0], given: 16

Re: Is [m]M<0[/m]? [#permalink] New post 06 Sep 2010, 19:34
Almost missed that M could be also 0 in S 1
_________________

Never give up,,,

Manager
Manager
avatar
Status: Keep fighting!
Affiliations: IIT Madras
Joined: 31 Jul 2010
Posts: 238
WE 1: 2+ years - Programming
WE 2: 3+ years - Product developement,
WE 3: 2+ years - Program management
Followers: 4

Kudos [?]: 182 [0], given: 104

Re: Is [m]M<0[/m]? [#permalink] New post 07 Sep 2010, 02:09
Good work Bunuel. I missed the zero consideration too!
Intern
Intern
avatar
Joined: 15 Aug 2010
Posts: 10
Followers: 0

Kudos [?]: 1 [0], given: 0

Re: Is [m]M<0[/m]? [#permalink] New post 07 Sep 2010, 03:48
1- Any thing equals to Modlus is always Positive, therefore, -M = must be a Positive number. this can only be possible when M itself is a -ve number.
Therefore Answer should be A

2- Option 2 would have 2 number + & -, therefore not sufficient

2-
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23330
Followers: 3599

Kudos [?]: 28589 [0], given: 2803

Re: Is [m]M<0[/m]? [#permalink] New post 07 Sep 2010, 04:08
Expert's post
harishsharma81 wrote:
1- Any thing equals to Modlus is always Positive, therefore, -M = must be a Positive number. this can only be possible when M itself is a -ve number.
Therefore Answer should be A

2- Option 2 would have 2 number + & -, therefore not sufficient

2-


Hi, and welcome to Gmat Club.

OA for this questionj is C not A (official answer is given under the spoiler in the first post).

Next, the red part is not correct: absolute value is always non-negative, which means that something equal to absolute value is either positive or zero. See my first post for the full solution of this question.

Hope it helps.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Senior Manager
Senior Manager
avatar
Joined: 29 Jan 2011
Posts: 387
Followers: 0

Kudos [?]: 57 [0], given: 87

Re: Is [m]M<0[/m]? [#permalink] New post 24 Sep 2011, 18:52
Bunuel wrote:
seekmba wrote:
Is M<0?

1. -M = |-M|
2. M^2 = 9

I got very confused with option 1 and took lot of time with this question. Can someone help me unedstand how I can solve such questions quickly.


Is m<0?

(1) -m=|-m| --> first of all |-m|=|m|, (for example: |-3|=|3|=3), so we have -m=|m|, as RHS is absolute value which is always non-negative, then LHS, {-m} must also be non-negative --> -m\geq{0} --> m\leq{0}, so m could be either negative or zero. Not sufficient.

(2) m^2=9 --> m=3=positive or m=-3=negative. Not sufficient.

(1)+(2) Intersection of the values from (1) and (2) is m=-3=negative, hence answer to the question "is m<0" is YES. Sufficient.

Answer: C.

Hope it's clear.



How do you get -m >= 0 => m <=0 ??? i dont understand
Manager
Manager
avatar
Joined: 21 Aug 2010
Posts: 209
Followers: 2

Kudos [?]: 13 [0], given: 28

Re: Is [m]M<0[/m]? [#permalink] New post 25 Sep 2011, 03:33
The answer is C but I also missed the Zero part.
As Bunuel says ZIP code
Manager
Manager
avatar
Status: Bell the GMAT!!!
Affiliations: Aidha
Joined: 16 Aug 2011
Posts: 186
Location: Singapore
Concentration: Finance, General Management
GMAT 1: 680 Q46 V37
GMAT 2: 620 Q49 V27
GMAT 3: 700 Q49 V36
WE: Other (Other)
Followers: 5

Kudos [?]: 39 [0], given: 43

Re: Is [m]M<0[/m]? [#permalink] New post 26 Sep 2011, 04:33
yeah..I also committed the classic error - missed the zero....grrrr!!!
_________________

If my post did a dance in your mind, send me the steps through kudos :)

My MBA journey at http://mbadilemma.wordpress.com/

Manager
Manager
avatar
Joined: 21 Aug 2010
Posts: 209
Followers: 2

Kudos [?]: 13 [0], given: 28

Re: Is [m]M<0[/m]? [#permalink] New post 26 Sep 2011, 10:28
GMATmission wrote:
yeah..I also committed the classic error - missed the zero....grrrr!!!



That is the most frequent mistake which we normally commit
Intern
Intern
avatar
Joined: 12 Feb 2012
Posts: 15
GMAT Date: 05-30-2012
GPA: 4
Followers: 0

Kudos [?]: 3 [0], given: 2

Re: absolute value [#permalink] New post 29 Apr 2012, 09:01
Statement 1: -M = |M|
M can either be any negative number, or Zero. Not Sufficient.

Statement 2: M^2=9
M can either be 3 or -3. Not Sufficient.

Together:
M must be either a negative number or zero AND either 3 or -3. M must be -3. Sufficient. Answer C

edit: swapped positive with negative. Below post is correct

Last edited by pstrench on 29 Apr 2012, 09:22, edited 1 time in total.
Intern
Intern
avatar
Joined: 22 Jan 2012
Posts: 35
Followers: 0

Kudos [?]: 12 [0], given: 0

Re: absolute value [#permalink] New post 29 Apr 2012, 09:10
1) Statement 1: -M = |M|

M can be either negative or zero.

as for M>0
-M is not equal to M
when M<0
-M = -(M)

Not sufficient.

2) Statement 2: M^2=9
M = 3 , -3
Not sufficient.

1&2) M= -3
Sufficient

C is the answer
Intern
Intern
avatar
Joined: 07 May 2011
Posts: 42
GMAT 1: Q V
GMAT 2: Q V
Followers: 0

Kudos [?]: 11 [0], given: 11

Re: Is [m]M<0[/m]? [#permalink] New post 27 Nov 2012, 18:54
Statement 1 looks confusing indeed. But it's good to get back to the basics. How is an absolute value defined?

|X|= X if X>=0 or -X if x<0. the reason for this definition is that absolute value is defined as being a non-negative value. it can be anything b a negative number.

Now,
|-M| looks strange. but think of -M as X. then |(-M)|= -M if (-M)>=0 or -(-M) if -M<0.
we are told that |-M|=-M. so the first condition applies. -M>=0. The question asks is M<0. -M>=0 is to say M<=0 (sign flipped). so yes, M< 0 but also M=0. So not sufficient.

Statement 2: we know that in this case, m could be +-3. so not sufficient.

taken together, we know from first statement that M is either negative or 0 and from the second statemnent that M is either plus or minus 3. clearly together, M is a negative number. Hence, C.



harishsharma81 wrote:
1- Any thing equals to Modlus is always Positive, therefore, -M = must be a Positive number. this can only be possible when M itself is a -ve number.
Therefore Answer should be A

2- Option 2 would have 2 number + & -, therefore not sufficient

2-
Manager
Manager
User avatar
Joined: 24 Mar 2010
Posts: 81
Followers: 0

Kudos [?]: 21 [0], given: 134

Re: Is [m]M<0[/m]? [#permalink] New post 20 Dec 2012, 07:06
samramandy wrote:
The answer is C but I also missed the Zero part.
As Bunuel says ZIP code


Bunuel,

Bestow your legendary wisdom upon this mortal, so that he too can know what ZIP code is.

P.S. M assuming Z - zero...whats the rest
_________________

- Stay Hungry, stay Foolish -

Expert Post
2 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23330
Followers: 3599

Kudos [?]: 28589 [2] , given: 2803

Re: Is [m]M<0[/m]? [#permalink] New post 20 Dec 2012, 07:17
2
This post received
KUDOS
Expert's post
eaakbari wrote:
samramandy wrote:
The answer is C but I also missed the Zero part.
As Bunuel says ZIP code


Bunuel,

Bestow your legendary wisdom upon this mortal, so that he too can know what ZIP code is.

P.S. M assuming Z - zero...whats the rest


ZIP - Zero, Integers, Positive numbers.

GMAT likes to act in -1<=x<=1 range. So:

Don't assume, with no ground for it, that variable cannot be Zero. Check 0!
Don't assume, with no ground for it, that variable is an Integer. Check fractions!
Don't assume, with no ground for it, that variable is Positive. Check negative values!
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Re: Is [m]M<0[/m]?   [#permalink] 20 Dec 2012, 07:17
    Similar topics Author Replies Last post
Similar
Topics:
Is M < 0? 1) -M = |-M| 2) M^2 = 9 BarneyStinson 4 25 Feb 2010, 19:49
Is M < 0 ? 1. -M = |-M| 2. M^2 = 9 Your thoughts and icandy 3 10 Oct 2008, 16:30
Is M < 0 ? (1) -M = |-M| (2) M^2 = 9 eyunni 20 20 Nov 2007, 11:07
Is M < 0? 1. -M = |-M| 2. M^2 =9 bmwhype2 10 21 Oct 2007, 19:47
1 |m+4|=2 m=? 1) m<0 2) m^2+8m+12=0 getzgetzu 12 05 May 2006, 23:25
Display posts from previous: Sort by

Is M<0? (1) -M = |-M| (2) M^2 = 9

  Question banks Downloads My Bookmarks Reviews Important topics  

Go to page    1   2    Next  [ 23 posts ] 



GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.