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

It is currently 16 Oct 2018, 13:52

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

Is 3^n > 2^k ?

  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: 49915
Is 3^n > 2^k ?  [#permalink]

Show Tags

New post 03 Jan 2016, 13:51
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

70% (01:34) correct 30% (01:22) wrong based on 127 sessions

HideShow timer Statistics

Director
Director
User avatar
Joined: 10 Mar 2013
Posts: 519
Location: Germany
Concentration: Finance, Entrepreneurship
GMAT 1: 580 Q46 V24
GPA: 3.88
WE: Information Technology (Consulting)
GMAT ToolKit User
Re: Is 3^n > 2^k ?  [#permalink]

Show Tags

New post 03 Jan 2016, 16:39
Bunuel wrote:
Is 3^n > 2^k ?

(1) k = n + 1
(2) n is a positive integer.


(1) k=n+1, k=2 and n=1 NO, k=3 and n=2 Yes, NOT SUFFICIENT
(2) n > 0, no info about k, which could be 1 or 100, NOT SUFFICIENT
(1)+(2) Still not sufficient considering the cases from (1)
Asnwer E
_________________

When you’re up, your friends know who you are. When you’re down, you know who your friends are.

Share some Kudos, if my posts help you. Thank you !

800Score ONLY QUANT CAT1 51, CAT2 50, CAT3 50
GMAT PREP 670
MGMAT CAT 630
KAPLAN CAT 660

Current Student
avatar
S
Joined: 30 Dec 2015
Posts: 188
Location: United States
Concentration: Strategy, Organizational Behavior
GPA: 3.88
WE: Business Development (Hospitality and Tourism)
Reviews Badge
Re: Is 3^n > 2^k ?  [#permalink]

Show Tags

New post 17 Jan 2016, 06:59
BrainLab wrote:
Bunuel wrote:
Is 3^n > 2^k ?

(1) k = n + 1
(2) n is a positive integer.


(1) k=n+1, k=2 and n=1 NO, k=3 and n=2 Yes, NOT SUFFICIENT
(2) n > 0, no info about k, which could be 1 or 100, NOT SUFFICIENT
(1)+(2) Still not sufficient considering the cases from (1)
Asnwer E



Hi! Can you elaborate on your answer?

I get 3 cases for statement 1

1. n=2 , k=3 9>8 - yes
2. n =3, k=4 27>16 - yes
3. n=-1, k=0 1/3 > 1 ? - no

So statement 2 tells us n is positive -- so why not c?

Thanks
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 6956
Re: Is 3^n > 2^k ?  [#permalink]

Show Tags

New post 17 Jan 2016, 07:20
lpetroski wrote:
BrainLab wrote:
Bunuel wrote:
Is 3^n > 2^k ?

(1) k = n + 1
(2) n is a positive integer.


(1) k=n+1, k=2 and n=1 NO, k=3 and n=2 Yes, NOT SUFFICIENT
(2) n > 0, no info about k, which could be 1 or 100, NOT SUFFICIENT
(1)+(2) Still not sufficient considering the cases from (1)
Asnwer E



Hi! Can you elaborate on your answer?

I get 3 cases for statement 1

1. n=2 , k=3 9>8 - yes
2. n =3, k=4 27>16 - yes
3. n=-1, k=0 1/3 > 1 ? - no

So statement 2 tells us n is positive -- so why not c?

Thanks


hi,
another option when n is positive and answer is NO..
n=1, k=2..3>4... no
so dont miss out few values
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html


GMAT online Tutor

Senior Manager
Senior Manager
avatar
S
Joined: 15 Jan 2017
Posts: 363
Re: Is 3^n > 2^k ?  [#permalink]

Show Tags

New post 09 Oct 2017, 11:35
Hi! Can you elaborate on your answer?

I get 3 cases for statement 1

1. n=2 , k=3 9>8 - yes
2. n =3, k=4 27>16 - yes
3. n=-1, k=0 1/3 > 1 ? - no

So statement 2 tells us n is positive -- so why not c?

Thanks[/quote]

hi,
another option when n is positive and answer is NO..
n=1, k=2..3>4... no
so dont miss out few values[/quote]


Hi, I thought the same case too. Here is my reasoning.

St 1: k = n + 1. Clearly insufficient, cause we don't have any case (positive and negative would have different outcomes)

St 2: n is positive integer. Means more than zero and positive ; hence cannot be 0 but is greater than one.

So one plus two statement means: k = n +1 and n is positive integer.
3^n > 2^n+1 (replacing k).
We get 3 to power 1 NOT GREATER than 2 to power 2. Then if n = 2; k = n +1 => k =2. So 3 to power is always less than 2 to power n +1.

Thus it is sufficient.
Request experts to help out on why E is correct, and point out the issue

Thank you
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 6956
Is 3^n > 2^k ?  [#permalink]

Show Tags

New post 09 Oct 2017, 17:36
1
Madhavi1990 wrote:
Hi! Can you elaborate on your answer?

I get 3 cases for statement 1

1. n=2 , k=3 9>8 - yes
2. n =3, k=4 27>16 - yes
3. n=-1, k=0 1/3 > 1 ? - no

So statement 2 tells us n is positive -- so why not c?

Thanks

hi,
another option when n is positive and answer is NO..
n=1, k=2..3>4... no
so dont miss out few values


Hi, I thought the same case too. Here is my reasoning.

St 1: k = n + 1. Clearly insufficient, cause we don't have any case (positive and negative would have different outcomes)

St 2: n is positive integer. Means more than zero and positive ; hence cannot be 0 but is greater than one.

So one plus two statement means: k = n +1 and n is positive integer.
3^n > 2^n+1 (replacing k).
We get 3 to power 1 NOT GREATER than 2 to power 2. Then if n = 2; k = n +1 => k =2. So 3 to power is always less than 2 to power n +1.

Thus it is sufficient.
Request experts to help out on why E is correct, and point out the issue

Thank you



Hi...
You are wrong at one point above..
When n=1, k =1+1=2.....3^1>2^2....NO
But when n=2 k=2+1=3...3^2>2^3... YES
Rather for all values of n above 2, Ans will be YES..

So ans is E as different answers possible
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html


GMAT online Tutor

GMAT Club Bot
Is 3^n > 2^k ? &nbs [#permalink] 09 Oct 2017, 17:36
Display posts from previous: Sort by

Is 3^n > 2^k ?

  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®.