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

It is currently 24 Oct 2014, 16:54

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

What is the largest prime factor of the sum of the series of

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Current Student
User avatar
Joined: 29 Jan 2005
Posts: 5252
Followers: 23

Kudos [?]: 140 [0], given: 0

Reviews Badge
What is the largest prime factor of the sum of the series of [#permalink] New post 11 Dec 2005, 03:02
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

100% (01:03) correct 0% (00:00) wrong based on 1 sessions
What is the largest prime factor of the sum of the series of consecutive integers from 1 to 30, inclusive?

A. 31
B. 17
C. 13
D. 11
E. 5

Please show your work.
Director
Director
avatar
Joined: 24 Oct 2005
Posts: 577
Location: NYC
Followers: 1

Kudos [?]: 16 [0], given: 0

 [#permalink] New post 11 Dec 2005, 03:05
sum of consecutive numbers. .
n*(n+1)/2

so. (30*31)/2

hence 31.. largest prime factor..at 5 in the morning. .
_________________

Success is my only option, failure is not -- Eminem

VP
VP
User avatar
Joined: 20 Sep 2005
Posts: 1023
Followers: 3

Kudos [?]: 24 [0], given: 0

 [#permalink] New post 13 Dec 2005, 14:21
Got 31 quickly but not as efficiently as bewakof.
Senior Manager
Senior Manager
avatar
Joined: 05 Oct 2005
Posts: 487
Followers: 1

Kudos [?]: 2 [0], given: 0

 [#permalink] New post 13 Dec 2005, 15:26
lhotseface wrote:
Got 31 quickly but not as efficiently as bewakof.


Bewakoof is not all that bewakoof after all :)
(bewakoof = dumb in Hindi/Urdu)
VP
VP
avatar
Joined: 06 Jun 2004
Posts: 1061
Location: CA
Followers: 2

Kudos [?]: 29 [0], given: 0

Re: PS Arithmetic progression [#permalink] New post 13 Dec 2005, 22:32
GMATT73 wrote:
What is the largest prime factor of the sum of the series of consecutive integers from 1 to 30, inclusive?

A. 31
B. 17
C. 13
D. 11
E. 5

Please show your work.


Answer is A

Sum = (# of integers) (average) = (30-1+1) (31/2) = 465 = 5*3*31

bewakoof, what are you doing up at 5am in the morning?



:lol:
Current Student
User avatar
Joined: 29 Jan 2005
Posts: 5252
Followers: 23

Kudos [?]: 140 [0], given: 0

Reviews Badge
Re: PS Arithmetic progression [#permalink] New post 13 Dec 2005, 23:05
TeHCM wrote:
GMATT73 wrote:
What is the largest prime factor of the sum of the series of consecutive integers from 1 to 30, inclusive?

A. 31
B. 17
C. 13
D. 11
E. 5

Please show your work.


Answer is A

Sum = (# of integers) (average) = (30-1+1) (31/2) = 465 = 5*3*31

bewakoof, what are you doing up at 5am in the morning?

5am? Give that man a 700!
Senior Manager
Senior Manager
User avatar
Joined: 14 Apr 2005
Posts: 422
Location: India, Chennai
Followers: 1

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

Re: PS Arithmetic progression [#permalink] New post 14 Dec 2005, 00:09
GMATT73 wrote:
What is the largest prime factor of the sum of the series of consecutive integers from 1 to 30, inclusive?

A. 31
B. 17
C. 13
D. 11
E. 5

Please show your work.


sum = n/2(a+l), where a is the first term, l is the last term, and n is the number of terms in the series.
= 30/2(1+30)
= 15 * 31
31 is a prime number, and factor of 15*31, hence A.
Re: PS Arithmetic progression   [#permalink] 14 Dec 2005, 00:09
    Similar topics Author Replies Last post
Similar
Topics:
What is the sum of the different positive prime factors of mbsnyc 2 17 Dec 2007, 16:23
What is the sum of all the factors of 12972960 yezz 3 12 Sep 2006, 11:16
1 On the GMATPrep software: What is the largest prime number lacey.griffith 4 26 Jul 2006, 19:23
What is the largest prime number that can divide evenly into GMATT73 9 16 Oct 2005, 00:02
If x = 2^74 2^70, what is the largest prime factor of x? nzgmat 2 05 Nov 2004, 16:28
Display posts from previous: Sort by

What is the largest prime factor of the sum of the series of

  Question banks Downloads My Bookmarks Reviews Important topics  


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®.