GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 22 Apr 2019, 23:10

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.

Close

Request Expert Reply

Confirm Cancel

If abc ≠ 0, is abc > 0 ?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 54440
If abc ≠ 0, is abc > 0 ?  [#permalink]

Show Tags

New post 11 Aug 2017, 01:19
00:00
A
B
C
D
E

Difficulty:

  95% (hard)

Question Stats:

35% (02:03) correct 65% (01:43) wrong based on 79 sessions

HideShow timer Statistics

Magoosh GMAT Instructor
User avatar
G
Joined: 28 Dec 2011
Posts: 4485
Re: If abc ≠ 0, is abc > 0 ?  [#permalink]

Show Tags

New post 11 Aug 2017, 17:06
1
Bunuel wrote:
If \(abc ≠ 0\), is \(abc > 0\) ?


(1) \(|a –b | = |a| - |b|\)

(2) \(|b + c| = |b| + |c|\)

A brilliant question!

Thanks,
Mike :-)
_________________
Mike McGarry
Magoosh Test Prep


Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)
Intern
Intern
avatar
Joined: 06 Jul 2017
Posts: 7
Re: If abc ≠ 0, is abc > 0 ?  [#permalink]

Show Tags

New post 11 Aug 2017, 17:55
from 2 you get that b,c should have the same sign therefore the question collapses to a>?0 NS.
from 1 you get that a,b should have same sign (try different signs and get contradiction) the question collapses to c>?0 NS.
Combine together, NS as if all tree positive then its true if all negative you get false.
WDYT?



Sent from my iPhone using GMAT Club Forum
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7578
Re: If abc ≠ 0, is abc > 0 ?  [#permalink]

Show Tags

New post 11 Aug 2017, 20:16
Bunuel wrote:
If \(abc ≠ 0\), is \(abc > 0\) ?


(1) \(|a –b | = |a| - |b|\)

(2) \(|b + c| = |b| + |c|\)


Hi..

Clearly each sentence talks of two variables, hence insufficient individually..

Combined..
(1) \(|a –b | = |a| - |b|\)
I tells us that a>b or a=b and also both a and B are of same sign.
You can square also to find it..
\(a^2+b^2-2ab=a^2+b^2-2|a||b|........ 2|a||b|-2ab=0...\)
So a*b is POSITIVE and both are of same SIGN.

(2) [m]|b + c| = |b| + |c|
Here B and C are of same sign.

So combined all three are of same SIGN..
But if all three are positive, and is YES
If all three are NEGATIVE, and is NO
Insuff

C
_________________
Manager
Manager
User avatar
G
Joined: 27 Dec 2016
Posts: 232
Concentration: Marketing, Social Entrepreneurship
GPA: 3.65
WE: Marketing (Education)
Reviews Badge
If abc ≠ 0, is abc > 0 ?  [#permalink]

Show Tags

New post 12 Aug 2017, 00:15
#STATEMENT 1
- Plugin value, we can get a&b both positive or a&b both negative.
- Hence, insufficient.

#STATEMENT 2
- Plugin value, we can get b&c both positive or b&c both negative.
- Hence, insufficient.

Anyway statement #1 and #2 only talk about 2 out of 3 variable - INSUFFICIENT from the begining.

#BOTH STATEMENT TOGETHER
We have two combinations :
1. a,b and c all POSITIVE = YES for the question.
2. a,b and c all NEGATIVE = NO for the question.
INSUFFICIENT

Therefore, the answer is E.

Is this correct? :oops: :oops: :oops:
_________________
There's an app for that - Steve Jobs.
Manager
Manager
User avatar
G
Joined: 27 Dec 2016
Posts: 232
Concentration: Marketing, Social Entrepreneurship
GPA: 3.65
WE: Marketing (Education)
Reviews Badge
Re: If abc ≠ 0, is abc > 0 ?  [#permalink]

Show Tags

New post 12 Aug 2017, 00:19
chetan2u wrote:
Bunuel wrote:
If \(abc ≠ 0\), is \(abc > 0\) ?


(1) \(|a –b | = |a| - |b|\)

(2) \(|b + c| = |b| + |c|\)


Hi..

Clearly each sentence talks of two variables, hence insufficient individually..

Combined..
(1) \(|a –b | = |a| - |b|\)
I tells us that a>b or a=b and also both a and B are of same sign.
You can square also to find it..
\(a^2+b^2-2ab=a^2+b^2-2|a||b|........ 2|a||b|-2ab=0...\)
So a*b is POSITIVE and both are of same SIGN.

(2) [m]|b + c| = |b| + |c|
Here B and C are of same sign.

So combined all three are of same SIGN..
But if all three are positive, and is YES
If all three are NEGATIVE, and is NO
Insuff

C


chetan2u

Why you choose C although both statement insufficient?
_________________
There's an app for that - Steve Jobs.
SVP
SVP
User avatar
V
Joined: 26 Mar 2013
Posts: 2137
Reviews Badge CAT Tests
Re: If abc ≠ 0, is abc > 0 ?  [#permalink]

Show Tags

New post 12 Aug 2017, 11:20
Bunuel wrote:
If \(abc ≠ 0\), is \(abc > 0\) ?


(1) \(|a –b | = |a| - |b|\)

(2) \(|b + c| = |b| + |c|\)


Let's take 2 & -2 and plug them across the statements (or choose any 2 values). I choose a number and its apposite to make calculations easy.

(1) \(|a –b | = |a| - |b|\)

(a,b) = (2, 2)
\(|2 –2 | = |2| - |2|\)= 0

(a,b) = (-2, -2)
\(|-2 +2 | = |2| - |2|\)= 0

(a,b) = (-2, 2) and (2,- 2) are invalid as RHS does not equal LHS

Conclusion is a & b must have same sign but c can be any number with any sign

Insufficient

(2) \(|b + c| = |b| + |c|\)

(b,c) = (2, 2)
\(|2 + 2| = |2| + |2|\)= 4

(b,c) = (-2,-2)
\(|-2 -2| = |-2| + |-2|\)= 4

(b,c) = (-2, 2) and (2,- 2) are invalid as RHS does not equal LHS

Conclusion is b & c must have same sign but a can be any number with any sign

Insufficient

Combining 1 & 2

Case I: 2, 2 , 2.................Answer is Yes

Case II: -2, -2,-2..............Answer is NO

Insufficient

Answer: E
Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 10599
Re: If abc ≠ 0, is abc > 0 ?  [#permalink]

Show Tags

New post 09 Apr 2019, 08:44
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
GMAT Club Bot
Re: If abc ≠ 0, is abc > 0 ?   [#permalink] 09 Apr 2019, 08:44
Display posts from previous: Sort by

If abc ≠ 0, is abc > 0 ?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Copyright

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

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

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®.