Find all School-related info fast with the new School-Specific MBA Forum

It is currently 02 Oct 2014, 03:34

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

For positive integer k, is the expression (k +

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Senior Manager
Senior Manager
User avatar
Joined: 22 Dec 2009
Posts: 365
Followers: 10

Kudos [?]: 209 [0], given: 47

GMAT ToolKit User
For positive integer k, is the expression (k + [#permalink] New post 21 Feb 2010, 13:40
1
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

46% (02:10) correct 54% (01:44) wrong based on 42 sessions
For positive integer k, is the expression (k + 2)(k^2 + 4k + 3) divisible by 4?

(1) k is divisible by 8.

(2) \frac{k + 1}{3} is an odd integer.

SOURCE: Manhattan Tests

[Reveal] Spoiler: OA
A


Please explain. A little doubtful with this OA
_________________

Cheers!
JT...........
If u like my post..... payback in Kudos!! :beer

|Do not post questions with OA|Please underline your SC questions while posting|Try posting the explanation along with your answer choice|
|For CR refer Powerscore CR Bible|For SC refer Manhattan SC Guide|


~~Better Burn Out... Than Fade Away~~

Expert Post
CEO
CEO
User avatar
Joined: 17 Nov 2007
Posts: 3571
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40
Followers: 365

Kudos [?]: 1809 [0], given: 358

GMAT ToolKit User Premium Member
Re: For positive integer k, is the expressio [#permalink] New post 21 Feb 2010, 13:55
Expert's post
1) if k is divisible by 8 (and by 4 too), then k+2 is even but isn't divisible by 4 or 8.
(k^2+4k+3) - an odd integer. ---> (even but not divisible by 4 or 8)*odd ---> the expression isn't divisible by 4.

2)k+1/3 is odd --> k+1 is odd --> k is even --> k+2 is even. if k+2:
- is divisible by 4, the expression is also divisible by 4
- isn't divisible by 4, the expression isn't divisible by 4
insufficient
_________________

HOT! GMAT TOOLKIT 2 (iOS) / GMAT TOOLKIT (Android) - The OFFICIAL GMAT CLUB PREP APP, a must-have app especially if you aim at 700+ | PrepGame

Senior Manager
Senior Manager
avatar
Joined: 25 Jun 2009
Posts: 313
Followers: 2

Kudos [?]: 74 [0], given: 6

Re: For positive integer k, is the expressio [#permalink] New post 22 Feb 2010, 11:57
jeeteshsingh wrote:
For positive integer k, is the expression (k + 2)(k^2 + 4k + 3) divisible by 4?

(1) k is divisible by 8.

(2) \frac{k + 1}{3} is an odd integer.

SOURCE: Manhattan Tests

[Reveal] Spoiler: OA
A


Please explain. A little doubtful with this OA


Another way of looking at it ..
the expression (k + 2)(k^2 + 4k + 3) can be written as (K+2)(K+1)(K+3)

which means they are consecutive numbers.

St1. K is divisible by 8 lets say K = 8

then the expression becomes 9*10*11 which is not divisible by 4, ( which holds for any value of K which is a multiple of 8)

Hence Sufficient

St 2 \frac{k + 1}{3} is an odd integer.

Which K + 1 is an odd integer lets take K=2

If K =2 then the expression is divisible by 4

but not lets assume K = 8 then then again the expression is not divisible by 4

Hence Insufficient.
Manager
Manager
avatar
Joined: 29 Oct 2009
Posts: 203
Concentration: General Management, Sustainability
WE: Consulting (Computer Software)
Followers: 2

Kudos [?]: 56 [0], given: 12

Re: For positive integer k, is the expressio [#permalink] New post 25 Feb 2010, 09:37
IMO it is A. I solved this the same way as nitishmahajan did.
Intern
Intern
User avatar
Joined: 03 Mar 2010
Posts: 40
Followers: 1

Kudos [?]: 10 [0], given: 1

Re: For positive integer k, is the expressio [#permalink] New post 12 Mar 2010, 07:30
IMO A

expression = (k+2)(k+1)(k+3)
(1): (k+1)(k+3) is odd integer, (k+2) is only divisible by 2 but not by 4 so (1) is sufficient!
(2): k=2 then expression=4*odd integer is divisible by 4
k=5 then expression=6*odd integer is not divisible by 4
_________________

Hardworkingly, you like my post, so kudos me.

Senior Manager
Senior Manager
User avatar
Status: Can't give up
Joined: 20 Dec 2009
Posts: 321
Followers: 2

Kudos [?]: 26 [0], given: 35

Re: For positive integer k, is the expressio [#permalink] New post 12 Mar 2010, 10:59
clearly A.

B) when k=8 8+1/3 = divisible; when k=14 14+1/3 not divisible. Insuff
1 KUDOS received
Manager
Manager
avatar
Joined: 21 Jan 2010
Posts: 233
Followers: 4

Kudos [?]: 49 [1] , given: 38

Re: For positive integer k, is the expressio [#permalink] New post 15 Mar 2010, 09:12
1
This post received
KUDOS
A. Same logic as the above.
Senior Manager
Senior Manager
User avatar
Joined: 19 Nov 2009
Posts: 329
Followers: 4

Kudos [?]: 60 [0], given: 44

Re: For positive integer k, is the expressio [#permalink] New post 15 Mar 2010, 21:51
Answer should be A.

Solved using a similar method as nitishmahajan's.
Manager
Manager
avatar
Joined: 27 Dec 2009
Posts: 172
Followers: 2

Kudos [?]: 27 [0], given: 3

Re: For positive integer k, is the expressio [#permalink] New post 25 Apr 2010, 00:12
nitishmahajan wrote:
jeeteshsingh wrote:
For positive integer k, is the expression (k + 2)(k^2 + 4k + 3) divisible by 4?

(1) k is divisible by 8.

(2) \frac{k + 1}{3} is an odd integer.

SOURCE: Manhattan Tests

[Reveal] Spoiler: OA
A


Please explain. A little doubtful with this OA


Another way of looking at it ..
the expression (k + 2)(k^2 + 4k + 3) can be written as (K+2)(K+1)(K+3)

which means they are consecutive numbers.

St1. K is divisible by 8 lets say K = 8

then the expression becomes 9*10*11 which is not divisible by 4, ( which holds for any value of K which is a multiple of 8)

Hence Sufficient

St 2 \frac{k + 1}{3} is an odd integer.

Which K + 1 is an odd integer lets take K=2

If K =2 then the expression is divisible by 4

but not lets assume K = 8 then then again the expression is not divisible by 4

Hence Insufficient.

good explanation...
Intern
Intern
avatar
Joined: 19 Jun 2010
Posts: 27
Followers: 0

Kudos [?]: 4 [0], given: 0

Re: For positive integer k, is the expressio [#permalink] New post 13 Jul 2010, 03:56
Another way to look at it:
i)k is divisible by 8, so k is also divisible by 4. From the property of consecutive multiple , we know that the next term that is divisible by 4 after k is (k+4) (that is every 4th number from k). That means (K+2)(K+1)(K+3) is not divisible by 4.

ii) k+2 is even, but we don't know if it is a multiple of 4 or not. Plug in 1 and 3 for k+1 yields different answer
Senior Manager
Senior Manager
User avatar
Joined: 25 Feb 2010
Posts: 459
Followers: 3

Kudos [?]: 35 [0], given: 5

Re: For positive integer k, is the expressio [#permalink] New post 13 Jul 2010, 07:18
nitishmahajan wrote:
jeeteshsingh wrote:
For positive integer k, is the expression (k + 2)(k^2 + 4k + 3) divisible by 4?

(1) k is divisible by 8.

(2) \frac{k + 1}{3} is an odd integer.

SOURCE: Manhattan Tests

[Reveal] Spoiler: OA
A


Please explain. A little doubtful with this OA


Another way of looking at it ..
the expression (k + 2)(k^2 + 4k + 3) can be written as (K+2)(K+1)(K+3)

which means they are consecutive numbers.

St1. K is divisible by 8 lets say K = 8

then the expression becomes 9*10*11 which is not divisible by 4, ( which holds for any value of K which is a multiple of 8)

Hence Sufficient

St 2 \frac{k + 1}{3} is an odd integer.

Which K + 1 is an odd integer lets take K=2

If K =2 then the expression is divisible by 4

but not lets assume K = 8 then then again the expression is not divisible by 4

Hence Insufficient.



Nice work...

I liked the factorization part, to get the consecutive numbers.
:clap:
_________________

GGG (Gym / GMAT / Girl) -- Be Serious

Its your duty to post OA afterwards; some one must be waiting for that...

Re: For positive integer k, is the expressio   [#permalink] 13 Jul 2010, 07:18
    Similar topics Author Replies Last post
Similar
Topics:
2 Experts publish their posts in the topic Can the positive integer k be expressed as the product of enigma123 10 11 Feb 2012, 19:08
6 Experts publish their posts in the topic For positive integer k, is the expression (k + 2)(k2 + 4k + amitgovin 10 30 Sep 2009, 10:53
4 Experts publish their posts in the topic For positive integer k, is the expression (k + 2)(k^2 + 4k + kishankolli 9 22 Sep 2009, 02:51
For positive integer k, is the expression (k + 2)(k2 + 4k + ventivish 3 30 Nov 2008, 09:41
For positive integer k, is the expression (k + dancinggeometry 6 16 Sep 2008, 06:38
Display posts from previous: Sort by

For positive integer k, is the expression (k +

  Question banks Downloads My Bookmarks Reviews Important topics  


cron

GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

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®.