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

It is currently 23 Sep 2018, 13:30

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 k is a positive integer, is square root of k an integer?

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

Hide Tags

Director
Director
avatar
Status: Finally Done. Admitted in Kellogg for 2015 intake
Joined: 25 Jun 2011
Posts: 505
Location: United Kingdom
Concentration: International Business, Strategy
GMAT 1: 730 Q49 V45
GPA: 2.9
WE: Information Technology (Consulting)
If k is a positive integer, is square root of k an integer?  [#permalink]

Show Tags

New post 07 Mar 2012, 15:55
2
1
00:00
A
B
C
D
E

Difficulty:

  75% (hard)

Question Stats:

44% (01:23) correct 56% (01:07) wrong based on 184 sessions

HideShow timer Statistics

If k is a positive integer, is \(\sqrt{k}\) an integer?

(1) \(1 < \sqrt{k} < 3\)

(2) \(k^2 < 16\)

How come the answer is C?

Statement 1 - The only value K can take is 2. So this is sufficient.

Statement 2 - is not sufficient as -4 < k < 4.

Where I am incorrect guys?

_________________

Best Regards,
E.

MGMAT 1 --> 530
MGMAT 2--> 640
MGMAT 3 ---> 610
GMAT ==> 730

Most Helpful Expert Reply
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 49320
Re: Integer K  [#permalink]

Show Tags

New post 07 Mar 2012, 16:06
7
2
enigma123 wrote:
If k is a positive integer, is \(\sqrt{k}\) an integer?

(1) \(1 < \sqrt{k} < 3\)

(2) \(k^2 < 16\)

How come the answer is C?

Statement 1 - The only value K can take is 2. So this is sufficient.

Statement 2 - is not sufficient as -4 < k < 4.

Where I am incorrect guys?


If k is a positive integer, is \(\sqrt{k}\) an integer?

(1) \(1 < \sqrt{k} < 3\). Square the given inequality: \(1<k<9\) --> \(k\) can be 2, 3, 4, 5, 6, 7, or 8. If \(k=4\) then \(\sqrt{k}\) is an integer, for other values it's not an integer. Not sufficient.

(2) \(k^2 < 16\) --> \(-4<k<4\), since it's also given that \(k\) is a positive integer, then \(k\) can be 1, 2 or 3. If \(k=1\) then the answer is YES but if \(k\) is 2 or 3 then the answer is NO. Not sufficient.

(1)+(2) Intersection of the values of \(k\) from (1) and (2) is 2 and 3, \(\sqrt{k}\) is NOT an integer for either of them. Sufficient.

Answer: C.
_________________

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

General Discussion
Current Student
User avatar
D
Joined: 12 Aug 2015
Posts: 2648
Schools: Boston U '20 (M)
GRE 1: Q169 V154
GMAT ToolKit User Premium Member
Re: If k is a positive integer, is square root of k an integer?  [#permalink]

Show Tags

New post 13 Mar 2016, 08:50
Board of Directors
User avatar
P
Joined: 17 Jul 2014
Posts: 2683
Location: United States (IL)
Concentration: Finance, Economics
GMAT 1: 650 Q49 V30
GPA: 3.92
WE: General Management (Transportation)
GMAT ToolKit User Premium Member Reviews Badge
Re: If k is a positive integer, is square root of k an integer?  [#permalink]

Show Tags

New post 06 Apr 2017, 12:42
Bunuel wrote:
enigma123 wrote:
If k is a positive integer, is \(\sqrt{k}\) an integer?

(1) \(1 < \sqrt{k} < 3\)

(2) \(k^2 < 16\)

How come the answer is C?

Statement 1 - The only value K can take is 2. So this is sufficient.

Statement 2 - is not sufficient as -4 < k < 4.

Where I am incorrect guys?


If k is a positive integer, is \(\sqrt{k}\) an integer?

(1) \(1 < \sqrt{k} < 3\). Square the given inequality: \(1<k<9\) --> \(k\) can be 2, 3, 4, 5, 6, 7, or 8. If \(k=4\) then \(\sqrt{k}\) is an integer, for other values it's not an integer. Not sufficient.

(2) \(k^2 < 16\) --> \(-4<k<4\), since it's also given that \(k\) is a positive integer, then \(k\) can be 1, 2 or 3. If \(k=1\) then the answer is YES but if \(k\) is 2 or 3 then the answer is NO. Not sufficient.

(1)+(2) Intersection of the values of \(k\) from (1) and (2) is 2 and 3, \(\sqrt{k}\) is NOT an integer for either of them. Sufficient.

Answer: C.


what a brilliant explanation...I answered E, but now I see why I made the mistake...
i thought that k^2 = 4, therefore sqrt(k) can be either a non-integer or an integer...
GMAT Club Bot
Re: If k is a positive integer, is square root of k an integer? &nbs [#permalink] 06 Apr 2017, 12:42
Display posts from previous: Sort by

If k is a positive integer, is square root of k an integer?

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

Events & Promotions

PREV
NEXT


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®.