BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Interesting GMATFix Problem-12

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Community Manager
Posts: 1048
Joined: Mon Aug 17, 2009 3:26 am
Location: India
Thanked: 51 times
Followed by:27 members
GMAT Score:670

Interesting GMATFix Problem-12

by arora007 » Tue Sep 21, 2010 12:53 pm
a is an odd integer and a notequalto -b. Is ( a^2/ |b+a| ) > a-b ?
1) ab=0
2) a^3 >a
https://www.skiponemeal.org/
https://twitter.com/skiponemeal
Few things are impossible to diligence & skill.Great works are performed not by strength,but by perseverance

pm me if you find junk/spam/abusive language, Lets keep our community clean!!
Top
Source: — Data Sufficiency |
Legendary Member
Posts: 2326
Joined: Mon Jul 28, 2008 3:54 am
Thanked: 173 times
Followed by:2 members
GMAT Score:710

by gmatmachoman » Wed Sep 22, 2010 3:11 am
This is not a EASY one arora bhai!!

st 1:
ab=0

a is an odd integer (Given); b = 0

LHS = a^2 / |( a+0)|

= a^2 / a -- ( This will always be a positive no:)

LHS = a

RHS : a-b

: a- 0
: a

Since we dont know teh sign of "a" we cant decide whether LHS is > RHS; for example if a = -1 then LHS is > RHS.
If a= 1, then LHS = RHS
Insufficient

St 2:
a^3 - a >0
a( a^2 -1)>0

which leads to a >0 or a^2 >1-- Here "a" can be postitive or negative.

No idea about b. So insufficient

Combining st1 & st2:

still , we are NOT sure of sign of "a".

So PicK E
Top
User avatar
Community Manager
Posts: 1048
Joined: Mon Aug 17, 2009 3:26 am
Location: India
Thanked: 51 times
Followed by:27 members
GMAT Score:670

by arora007 » Wed Sep 22, 2010 3:28 am
yeah machoman... its not easy... and the OA is C
https://www.skiponemeal.org/
https://twitter.com/skiponemeal
Few things are impossible to diligence & skill.Great works are performed not by strength,but by perseverance

pm me if you find junk/spam/abusive language, Lets keep our community clean!!
Top
Legendary Member
Posts: 2326
Joined: Mon Jul 28, 2008 3:54 am
Thanked: 173 times
Followed by:2 members
GMAT Score:710

by gmatmachoman » Wed Sep 22, 2010 3:29 am
arora007 wrote:yeah machoman... its not easy... and the OA is C

dude,,.. Iam going NUTS now!!

all the DS of GMATfix tripped me!!
Top
Legendary Member
Posts: 2326
Joined: Mon Jul 28, 2008 3:54 am
Thanked: 173 times
Followed by:2 members
GMAT Score:710

by gmatmachoman » Wed Sep 22, 2010 3:34 am
arora007 wrote:yeah machoman... its not easy... and the OA is C
dude, i am not doubting patrick..but can u plz post OE for this one..
Top
User avatar
Community Manager
Posts: 1048
Joined: Mon Aug 17, 2009 3:26 am
Location: India
Thanked: 51 times
Followed by:27 members
GMAT Score:670

by arora007 » Wed Sep 22, 2010 3:48 am
Image
https://www.skiponemeal.org/
https://twitter.com/skiponemeal
Few things are impossible to diligence & skill.Great works are performed not by strength,but by perseverance

pm me if you find junk/spam/abusive language, Lets keep our community clean!!
Top
User avatar
Community Manager
Posts: 1048
Joined: Mon Aug 17, 2009 3:26 am
Location: India
Thanked: 51 times
Followed by:27 members
GMAT Score:670

by arora007 » Wed Sep 22, 2010 3:49 am
I guess the last 2-3 steps would have confused...have a closer look...
https://www.skiponemeal.org/
https://twitter.com/skiponemeal
Few things are impossible to diligence & skill.Great works are performed not by strength,but by perseverance

pm me if you find junk/spam/abusive language, Lets keep our community clean!!
Top
User avatar
Legendary Member
Posts: 1460
Joined: Tue Dec 29, 2009 1:28 am
Thanked: 135 times
Followed by:7 members

by selango » Wed Sep 22, 2010 4:26 am
I am not sure my approach is right.Please correct me I I am wrong.

stmt1,

ab=0

Since we know a is an odd integer ,b=0

LHS=a^2/|a|=a^2/a which is +ve

RHS=a

We dont know sign of a

Insuff

stmt2,

a^3>a

This implies a must be +ve.But we dont know value and sign of b.

Insuff

Combining 1 and 2,

ab=0 and a^3>a

we know a is +ve odd integer and b=0

LHS=a^2/|a|=a^2/a which is +ve

RHS=a,which is +ve.

( a^2/ |b+a| ) = a-b

Suff

Pick C
--Anand--
Top
User avatar
Community Manager
Posts: 1048
Joined: Mon Aug 17, 2009 3:26 am
Location: India
Thanked: 51 times
Followed by:27 members
GMAT Score:670

by arora007 » Wed Sep 22, 2010 5:00 am
read the FOIL-> "Is a^2 > a^2-b^2"
where b is zero
the answer is no,
thus it gives the answer to
Is ( a^2/ |b+a| ) > a-b , answer is No. pick C.
https://www.skiponemeal.org/
https://twitter.com/skiponemeal
Few things are impossible to diligence & skill.Great works are performed not by strength,but by perseverance

pm me if you find junk/spam/abusive language, Lets keep our community clean!!
Top

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 645
Joined: Mon Jul 26, 2010 12:42 pm
Location: US
Thanked: 527 times
Followed by:227 members

by e-GMAT » Wed Sep 22, 2010 5:49 am
gmatmachoman, your analysis is all correct and you would get the answer as C as well if you plug the condition that a is an "odd integer" in a^3 > a. This means that a is positive and > 1.

Hope that helps.

-Payal
Top
Legendary Member
Posts: 2326
Joined: Mon Jul 28, 2008 3:54 am
Thanked: 173 times
Followed by:2 members
GMAT Score:710

by gmatmachoman » Sun Dec 12, 2010 10:21 pm
e-GMAT wrote:gmatmachoman, your analysis is all correct and you would get the answer as C as well if you plug the condition that a is an "odd integer" in a^3 > a. This means that a is positive and > 1.

Hope that helps.

-Payal

Yes!! Payal...Somehow i didn't see this reply..now i understood y i am missing my target !!

I am too careless!!!
Top
Post new topic Post Reply
• Page 1 of 1