It is currently 25 Jun 2017, 07:26

### 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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# GMATprep DS: progression

 post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
Manager
Joined: 17 Aug 2009
Posts: 226
GMATprep DS: progression [#permalink]

### Show Tags

29 Dec 2009, 05:50
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 100% (00:08) wrong based on 3 sessions

### HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

Need help on this one (attached) -
Attachments

GMATPrep AP.doc [69 KiB]
Downloaded 228 times

 To download please login or register as a user

Manager
Joined: 09 May 2009
Posts: 205
Re: GMATprep DS: progression [#permalink]

### Show Tags

29 Dec 2009, 08:58
IMO D

for k =odd $$a_k$$ will be $$a_1$$ =1 ; $$a_3$$=3 ; $$a_5$$=5 ; so on

for k=even $$a_k$$=-$$a_(k-1)$$ will be $$a_2$$=-$$a_1$$=-1; $$a_4$$=-3 ; $$a_6$$=-5 :SO ON

SEQUENCE will be

1-1+3-3+5-5+7-7 ( when n is even sum=0 and when n=odd sum=n)

s1) for all n=odd sum=n and hence it is either +1,+3,+5,+7.....SO ON BUT ALL +VE
HENCE SUFF

s2)if $$a_n$$ is +ve -----> n is odd and hence sum is +ve =n
hence suff
_________________

GMAT is not a game for losers , and the moment u decide to appear for it u are no more a loser........ITS A BRAIN GAME

Manager
Joined: 17 Aug 2009
Posts: 226
Re: GMATprep DS: progression [#permalink]

### Show Tags

29 Dec 2009, 09:42
Thanks guys
OA is
[Reveal] Spoiler:
D
Re: GMATprep DS: progression   [#permalink] 29 Dec 2009, 09:42
Display posts from previous: Sort by

# GMATprep DS: progression

 post reply Question banks Downloads My Bookmarks Reviews Important topics

 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®.