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

It is currently 18 Jan 2019, 07:58

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
Events & Promotions in January
PrevNext
SuMoTuWeThFrSa
303112345
6789101112
13141516171819
20212223242526
272829303112
Open Detailed Calendar
  • Free GMAT Strategy Webinar

     January 19, 2019

     January 19, 2019

     07:00 AM PST

     09:00 AM PST

    Aiming to score 760+? Attend this FREE session to learn how to Define your GMAT Strategy, Create your Study Plan and Master the Core Skills to excel on the GMAT.
  • FREE Quant Workshop by e-GMAT!

     January 20, 2019

     January 20, 2019

     07:00 AM PST

     07:00 AM PST

    Get personalized insights on how to achieve your Target Quant Score.

If n and k are integers and (-2)n^5 > 0, is k^37 < 0?

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

Hide Tags

 
Intern
Intern
avatar
Joined: 09 Feb 2012
Posts: 49
Location: India
Concentration: Marketing, Strategy
GMAT 1: 640 Q48 V31
GPA: 3.45
WE: Marketing (Pharmaceuticals and Biotech)
If n and k are integers and (-2)n^5 > 0, is k^37 < 0?  [#permalink]

Show Tags

New post 04 Mar 2012, 21:11
4
1
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

64% (01:15) correct 36% (01:21) wrong based on 235 sessions

HideShow timer Statistics

If n and k are integers and (-2)n^5 > 0, is k^37 < 0?

(1) (nk)^z > 0, where z is an integer that is not divisible by two
(2) k < n
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 52284
Re: If n and k are integers and (-2)n^5 > 0, is k^37 < 0?  [#permalink]

Show Tags

New post 04 Mar 2012, 23:56
1
1
If n and k are integers and (-2)n^5 > 0, is k^37 < 0?

First of all: \((-2)*n^5>0\) --> reduce by negative -2 and flip the sign: \(n^5<0\) --> \(n<0\);
Next: "is \(k^{37}<0\)" basically means whether \(k<0\).

So the question becomes: If n and k are integers and \(n<0\) is \(k<0\)?

(1) (nk)^z > 0, where z is an integer that is not divisible by two --> \((nk)^{odd} > 0\) --> \(nk> 0\) --> \(n\) and \(k\) have the same sign and since \(n<0\) then \(k<0\). Sufficient.

(2) k < n --> since given that \(n<0\) then \(k<n<0\). Sufficient.

Answer: D.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

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?
Extra-hard Quant Tests with Brilliant Analytics

Board of Directors
User avatar
P
Joined: 01 Sep 2010
Posts: 3281
Re: If n and k are integers and (-2)n^5 > 0, is k^37 < 0?  [#permalink]

Show Tags

New post 22 Jun 2012, 13:54
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 52284
Re: If n and k are integers and (-2)n^5 > 0, is k^37 < 0?  [#permalink]

Show Tags

New post 23 Jun 2012, 02:58
1
carcass wrote:
Bunuel I find this question on the net.......I would like to know if you think that is a good question and if it is elaborate in a good manner.

It is important to practice. :)

Thanks


Though the question is testing basic concepts usual for the GMAT, I still wouldn't call that question very elegant.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

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?
Extra-hard Quant Tests with Brilliant Analytics

Intern
Intern
avatar
Joined: 21 Feb 2013
Posts: 1
Re: If n and k are integers and (-2)n^5 > 0, is k^37 < 0?  [#permalink]

Show Tags

New post 11 Mar 2013, 17:37
What about the possibility that Z is equal to 0. In that case 1) would be insufficient.
Verbal Forum Moderator
User avatar
B
Joined: 10 Oct 2012
Posts: 611
Premium Member
Re: If n and k are integers and (-2)n^5 > 0, is k^37 < 0?  [#permalink]

Show Tags

New post 11 Mar 2013, 20:47
thekid1998 wrote:
What about the possibility that Z is equal to 0. In that case 1) would be insufficient.

Z can't be zero as it is mentioned that z is not divisible by 2.
_________________

All that is equal and not-Deep Dive In-equality

Hit and Trial for Integral Solutions

Intern
Intern
User avatar
Status: Currently Preparing the GMAT
Joined: 15 Feb 2013
Posts: 29
Location: United States
GMAT 1: 550 Q47 V23
GPA: 3.7
WE: Analyst (Consulting)
Re: If n and k are integers and (-2)n^5 > 0, is k^37 < 0?  [#permalink]

Show Tags

New post 12 Mar 2013, 06:26
Another great DS problem that helps pinpoint the need to stay alert at the sign of the base of the exponent and whether the power itself is odd or even.

Let's begin by understanding the problem.

We have \(-2*(n)^5 > 0\). Since the power is odd and the end result is positive despite multiplying the expression \(n^5\) by (-2), then this states that n is negative.
So we want to see whether \(k^(37)<0\), which is translated to : is k negative ? since 37 is an odd number !

Statement 1 : \((nk)^z > 0\), where z is an integer that is not divisible by two

Since z is odd and the expression is positive, we can assume that the base, nk, is positive. And seeing as n is negative, we can say that k is also negative. And since 37 is an odd power, then \(k^(37)\) is negative. So statement 1 is sufficient.

Statement 2 : \(k < n\)

Since n is negative, it naturally follows that k is also negative. And since 37 is an odd power, then \(k^(37)\) is negative. So statement 2 is sufficient.

The correct answer is, therefore, D !

Hope that helped :-D .
Manager
Manager
avatar
S
Joined: 08 Oct 2018
Posts: 63
Location: India
GPA: 4
WE: Brand Management (Health Care)
If n and k are integers and (-2)n5 > 0, is k37 < 0? (nk)z > 0, where z  [#permalink]

Show Tags

New post 11 Jan 2019, 23:22
1
UB001 wrote:
If n and k are integers and (-2)n^5 > 0, is k^37 < 0?

1. (nk)^z > 0, where z is an integer that is not divisible by two
2. k < n


Analysing question stem
(-2)n^5 > 0...means 'n' is negative because only then the product of -2 and n will be positive integer...and the sign of integer raised to odd power will be same as sign of the integer.

So n < 0 .....(A)

Find:
k^37 < 0?
That is, Is k < 0?

Statement 1:
(nk)^z > 0 ...and z is odd.
That is... Product of negative "n" and "k" raised to odd integer "z" is positive.
This is possible only when k is negative, because only then the product n*k will pe positive...and (n*k)^odd integer will be greater than 0.
Hence, sufficient.

Statement 2:
k < n
Since 'n is less than 0 (from question stem analysis), k is also less than 0.
Hence k^37 < 0
Sufficient

Ans: D
_________________

We learn permanently when we teach,
We grow infinitely when we share.

Manager
Manager
avatar
S
Joined: 09 Mar 2018
Posts: 201
Location: India
Re: If n and k are integers and (-2)n5 > 0, is k37 < 0? (nk)z > 0, where z  [#permalink]

Show Tags

New post 11 Jan 2019, 23:29
1
UB001 wrote:
If n and k are integers and (-2)n^5 > 0, is k^37 < 0?

1. (nk)^z > 0, where z is an integer that is not divisible by two
2. k < n


So, before solving the question, lets brain storm over it a bit

If n and k are integers and (-2)n^5 > 0
That will imply that n will be -ive
(-2) * (-I)^5 will only give something > 0

Statement (1)
(nk)^z > 0, where z is an integer that is not divisible by two
z will be 1,3,5,7
here k will be - ive, (-n* -k)^Odd Integer, will give something > 0

When value of k^37 < 0, is put back in the question, it will be sufficient.

Statement (2)
k < n, Since n is -ive
k will be -ive

(-ive k)^ 37 < 0, will always be less than 0, it will be sufficient


Answer D
_________________

If you notice any discrepancy in my reasoning, please let me know. Lets improve together.

Quote which i can relate to.
Many of life's failures happen with people who do not realize how close they were to success when they gave up.

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 52284
Re: If n and k are integers and (-2)n^5 > 0, is k^37 < 0?  [#permalink]

Show Tags

New post 12 Jan 2019, 02:27
GMAT Club Bot
Re: If n and k are integers and (-2)n^5 > 0, is k^37 < 0? &nbs [#permalink] 12 Jan 2019, 02:27
Display posts from previous: Sort by

If n and k are integers and (-2)n^5 > 0, is k^37 < 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®.