NEW HERE? LEARN MORE
closeclose
Last visit was: 24 Apr 2024, 06:49 It is currently 24 Apr 2024, 06:49
Decision Tracker
My Rewards
New posts
New comers' posts

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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

Is ab<1? (1) a^2b<a (2) ab^2<b

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
User avatar
L
GMATNinja
GMAT Club Verbal Expert
Joined: 13 Aug 2009
Status: GMAT/GRE/LSAT tutors
Posts: 6917
Own Kudos [?]: 63653 [5]
Given Kudos: 1773
Location: United States (CO)
GMAT 1: 780 Q51 V46
GMAT 2: 800 Q51 V51
GRE 1: Q170 V170

GRE 2: Q170 V170
Send PM
Is ab<1? (1) a^2b<a (2) ab^2<b [#permalink] New post   18 Apr 2022, 00:26
1
Kudos
4
Bookmarks
Expert Reply
00:00
A
B
C
D
E

Difficulty:

75% (hard)

Question Stats:

51% (01:52) correct 49% (01:46) wrong based on 131 sessions
Hide Show timer Statistics
Is \(ab<1\)?

(1) \(a^2b<a\)
(2) \(ab^2<b\)
ShowHide Answer
Official Answer
E
User avatar
L
Archit3110
GMAT Club Legend
GMAT Club Legend
Joined: 18 Aug 2017
Status:You learn more from failure than from success.
Posts: 8019
Own Kudos [?]: 4095 [0]
Given Kudos: 242
Location: India
Concentration: Sustainability, Marketing
GMAT Focus 1:
545 Q79 V79 DI73
GPA: 4
WE:Marketing (Energy and Utilities)
Send PM
GMAT ToolKit User CAT Tests
Re: Is ab<1? (1) a^2b<a (2) ab^2<b [#permalink] New post   18 Apr 2022, 01:52
GMATNinja wrote:
Is \(ab<1\)?

(1) \(a^2b<a\)
(2) \(ab^2<b\)


target is ab<1
possible when either of them is -ve or 0 or fraction value of both
#2
a^2b<a
a*(ab-1)<0
possible when a is -ve or b is -ve & a is +ve or a is +ve (0<a<1) but b is 0 or both a,b are -ve such that value of ab>1
insufficient
#2
same as #1
insufficient
from 1 &2 we do not get anything in common
insufficient
option E
User avatar
B
ColumbiaBaby
Intern
Intern
Joined: 23 Feb 2020
Posts: 26
Own Kudos [?]: 6 [0]
Given Kudos: 24
Location: India
Schools: Booth '25 (A) Wharton '25 (A) CBS '25 (WL) Stanford '25 (II)
GMAT 1: 740 Q49 V42
GPA: 4
Send PM
Is ab<1? (1) a^2b<a (2) ab^2<b [#permalink] New post   26 May 2022, 09:58
GMATNinja chetan2u Archit3110 shouldn't this be c?

#1 gives a<0 or ab<1 and #2 gives b<0 or ab<1

ab<1 is common between the two.

Please let me know where I'm going wrong. thanks
User avatar
L
chetan2u
RC & DI Moderator
Joined: 02 Aug 2009
Status:Math and DI Expert
Posts: 11168
Own Kudos [?]: 31883 [3]
Given Kudos: 290
Send PM
Reviews Badge
Is ab<1? (1) a^2b<a (2) ab^2<b [#permalink] New post   26 May 2022, 11:12
3
Kudos
Expert Reply
Is \(ab<1\)?

(1) \(a^2b<a………a^2b-a<0………a(ab-1)<0\)
Two ways:
a<0 and ab-1>0, that is ab>1. Thus, a<0, b<0 and ab>1
a>0 and ab-1<0, that is ab<1. Thus, a>0, b<0 and ab<1.

(2) \(ab^2<b……b(ab-1)<0\)
Same as statement 1.
Two ways:
b<0 and ab-1>0, that is ab>1. Thus, a<0, b<0 and ab>1
b>0 and ab-1<0, that is ab<1. Thus, a<0, b>0 and ab<1.

Nothing new when combined.

E

ColumbiaBaby, you are slightly wrong in analysing the statements.

Take an example.
Let a=b=-2, then \((-2)^3<-2\) or \(-8<-2\)….Yes
Let a=b=-1, then \((-1)^3<-1\) or \(-1<-1\)….No
User avatar
B
ColumbiaBaby
Intern
Intern
Joined: 23 Feb 2020
Posts: 26
Own Kudos [?]: 6 [0]
Given Kudos: 24
Location: India
Schools: Booth '25 (A) Wharton '25 (A) CBS '25 (WL) Stanford '25 (II)
GMAT 1: 740 Q49 V42
GPA: 4
Send PM
Re: Is ab<1? (1) a^2b<a (2) ab^2<b [#permalink] New post   26 May 2022, 11:18
Ah got it! I solved it like a normal quadratic and not like an inequality.

Thank you!
User avatar
B
aditiagg
Intern
Intern
Joined: 09 Apr 2022
Posts: 7
Own Kudos [?]: 0 [0]
Given Kudos: 2
Send PM
Re: Is ab<1? (1) a^2b<a (2) ab^2<b [#permalink] New post   17 Aug 2022, 19:53
ColumbiaBaby wrote:
GMATNinja chetan2u Archit3110 shouldn't this be c?

#1 gives a<0 or ab<1 and #2 gives b<0 or ab<1

ab<1 is common between the two.

Please let me know where I'm going wrong. thanks



This is what I'm doing and still not sure why the answer is not C
User avatar
L
chetan2u
RC & DI Moderator
Joined: 02 Aug 2009
Status:Math and DI Expert
Posts: 11168
Own Kudos [?]: 31883 [1]
Given Kudos: 290
Send PM
Reviews Badge
Re: Is ab<1? (1) a^2b<a (2) ab^2<b [#permalink] New post   17 Aug 2022, 21:12
1
Kudos
Expert Reply
aditiagg wrote:
ColumbiaBaby wrote:
GMATNinja chetan2u Archit3110 shouldn't this be c?

#1 gives a<0 or ab<1 and #2 gives b<0 or ab<1

ab<1 is common between the two.

Please let me know where I'm going wrong. thanks



This is what I'm doing and still not sure why the answer is not C


Statement I gives you two informations
If a<0, then ab-1>0 or ab>1, but if a>0, then ab-1<0 or ab<1.
Similarly for statement II.

Combined too, we get ab>1 or ab<1.
Only thing you can say is that \(ab\neq 1\)
GMAT Club Bot
gmatclubot
Re: Is ab<1? (1) a^2b<a (2) ab^2<b [#permalink]
17 Aug 2022, 21:12
Moderator:
Bunuel
Math Expert
92901 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions