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

It is currently 15 Sep 2014, 01:44

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

Numbers 8

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Manager
Manager
avatar
Joined: 19 Aug 2009
Posts: 81
Followers: 1

Kudos [?]: 50 [0], given: 46

Numbers 8 [#permalink] New post 06 Nov 2009, 05:13
1
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 100% (10:19) wrong based on 1 sessions
Q.Define a mumber K such that it is the sum of the squares of the 1st M natural numbers ie (k=1^2 + 2^2 +...M^2) where M<55. How many values of M exist such that K is divisibl by 4?

1.10
2.11
3.12

( its not possibl to check individually...whats da logic)
1 KUDOS received
Intern
Intern
avatar
Affiliations: CA - India
Joined: 27 Oct 2009
Posts: 46
Location: India
Schools: ISB - Hyderabad, NSU - Singapore
Followers: 9

Kudos [?]: 420 [1] , given: 5

Re: Numbers 8 [#permalink] New post 06 Nov 2009, 05:35
1
This post received
KUDOS
Look at it this way, sum of squares of first n no = [n(n+1)(2n+1)]/6. You know this, right? This is represented in the question to be K.

So now, K to be divisible by 4, must have atleast one out of n, n+1 to be divisbile by 4*2 (because it should also be divisible by 2*3) or 8. Dont worry about divisbility by 3, as one of the three numbers, n, n+1 and 2n+1 is always divisible by 3.

So we get pairs such as m =7 or 8, 15 or 16 ... upto 47 or 48. Thus total number of values of m satisfying condition for K's divisibility by 4, will be 12.

OA should be C.
Re: Numbers 8   [#permalink] 06 Nov 2009, 05:35
    Similar topics Author Replies Last post
Similar
Topics:
2 In a hostel, the number of students decreased by 8% and the gmihir 4 01 May 2012, 20:22
1 Experts publish their posts in the topic The number of rectangles that can be formed on a 8X8 chessbo saurabhgoel 6 13 Sep 2010, 22:43
GMAT Number Properties 8 gmatjon 2 24 Sep 2009, 07:26
A sum of money invested for a certain number of years at 8% christoph 2 11 May 2005, 12:32
A certain number when successfully divided by 8 and 11 christoph 1 06 May 2005, 05:13
Display posts from previous: Sort by

Numbers 8

  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®.