Stumped on this Data Sufficiency question... : Quant Question Archive [LOCKED]
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 24 Jan 2017, 03:46

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

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

Stumped on this Data Sufficiency question...

Author Message
Intern
Joined: 10 Apr 2008
Posts: 4
Followers: 0

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

Stumped on this Data Sufficiency question... [#permalink]

Show Tags

10 Apr 2008, 10:09
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

This question came from math bin 3 in the Princeton Review 2008 book.

If P is a set of integers and 3 is in P, is every positive multiple of 3 in P?

1) For any integer in P, the sum of 3 and that integer is also in P.
2) For any integer in P, that integer minus 3 is also in P.

My reasoning is that each statement alone is sufficient, because...

stmt. 1 - any positive multiple of 3 is included because it could be 0 + 3 = 3, 3 + 3 = 6...., 9 + 3 = 12, etc.

stmt. 2- this could be 3 - 3 = 0, 6 - 3 = 3, and so on. so all positive multiples of 3 should also be included right?

According to the PR explanations, statement 2 gives all the negative multiples of 3 and that the correct answer is:
statement 1 alone is sufficient, but statement 2 alone is not sufficient.

Is this an error in the book or am I completely overlooking something?
Director
Joined: 10 Sep 2007
Posts: 947
Followers: 8

Kudos [?]: 287 [0], given: 0

Re: Stumped on this Data Sufficiency question... [#permalink]

Show Tags

10 Apr 2008, 12:28
As per question If P is a set of integers and 3 is in P. Let us assume that to start with P contains only 3.

Statement 1:
Tells us that for any integer in P, the sum of 3 and that integer is also in P. As we already have 3 as part of P, so what follows is we have 3+3 = 6, 6+3 =9, 9+3 = 12...... etc. as part of P. So question is answered.

Statement 2:
Tells us for any integer in P, that integer minus 3 is also in P. As we already have 3 as part of P, so what follows is we have 3-3 = 0, 0-3 = -3, -3-3 = -6,....etc. as part of P. So question is not answered.

Intern
Joined: 10 Apr 2008
Posts: 4
Followers: 0

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

Re: Stumped on this Data Sufficiency question... [#permalink]

Show Tags

10 Apr 2008, 13:37
ty. that makes much better sense now.
Director
Joined: 05 Jan 2008
Posts: 701
Followers: 5

Kudos [?]: 417 [0], given: 0

Re: Stumped on this Data Sufficiency question... [#permalink]

Show Tags

10 Apr 2008, 15:25
For any integer in P, the sum of 3 and that integer is also in P.

why are you not considering numbers 1,2,4,5 in Stmt-1
_________________

Persistence+Patience+Persistence+Patience=G...O...A...L

Intern
Joined: 10 Apr 2008
Posts: 4
Followers: 0

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

Re: Stumped on this Data Sufficiency question... [#permalink]

Show Tags

10 Apr 2008, 18:46
prasannar wrote:
For any integer in P, the sum of 3 and that integer is also in P.

why are you not considering numbers 1,2,4,5 in Stmt-1

I get it now... the question only confirms that the number 3 is in the set. so only 3, 3+3 or 6, 6+3 or 9, 9+3 or 12, etc. are in this set according to statement 1.
SVP
Joined: 04 May 2006
Posts: 1926
Schools: CBS, Kellogg
Followers: 23

Kudos [?]: 1014 [0], given: 1

Re: Stumped on this Data Sufficiency question... [#permalink]

Show Tags

10 Apr 2008, 18:54
prasannar wrote:
why are you not considering numbers 1,2,4,5 in Stmt-1
For any integer in P, the sum of 3 and that integer is also in P.

why are you not considering numbers 1,2,4,5 in Stmt-1

Argree with prasannar,
No clues say that you must start from 3+3! Why not from 3+2?
_________________
Director
Joined: 10 Sep 2007
Posts: 947
Followers: 8

Kudos [?]: 287 [0], given: 0

Re: Stumped on this Data Sufficiency question... [#permalink]

Show Tags

11 Apr 2008, 04:31
prasannar wrote:
For any integer in P, the sum of 3 and that integer is also in P.

why are you not considering numbers 1,2,4,5 in Stmt-1

Question is asking abouy whether all the +ve multiples of 3 is present in series or not. Which we can answer from the information present in the question. Even if 1,2 etc. are there that would not add much value in answering the question.
Senior Manager
Joined: 02 Dec 2007
Posts: 457
Followers: 2

Kudos [?]: 197 [0], given: 6

Re: Stumped on this Data Sufficiency question... [#permalink]

Show Tags

11 Apr 2008, 07:59
With the same logic, statement 2 can be proved as well. Not sure why the answer is A .
The multiples of 3 may or may not be present in either of the statements.

Ama have to go with E here folks .

Explanation anyone ?
Re: Stumped on this Data Sufficiency question...   [#permalink] 11 Apr 2008, 07:59
Display posts from previous: Sort by