NEW HERE? LEARN MORE
closeclose
Last visit was: 24 Apr 2024, 04:52 It is currently 24 Apr 2024, 04:52
Decision Tracker
My Rewards
New posts
New comers' posts

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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

M25 - Question #10

User avatar
stilite
Intern
Intern
Joined: 26 Aug 2009
Posts: 14
Own Kudos [?]: 4 [0]
Given Kudos: 3
Send PM
M25 - Question #10 [#permalink] New post   30 Oct 2009, 09:32
Forgive me if I am wrong, but I truly believe the answer to this question to be "D."

The stimulus is asking:

Is the standard deviation of T positive?

Well,... stem question #1 clearly states that all elements of set T are positive. Thus, it is given that the ultimate standard deviation of set T is, in fact, positive.


Am I wrong?

Archived Topic
Hi there,
Archived GMAT Club Tests question - no more replies possible.
Where to now? Try our up-to-date Free Adaptive GMAT Club Tests for the latest questions.
Still interested? Check out the "Best Topics" block below for better discussion and related questions.
Thank you for understanding, and happy exploring!
User avatar
hogann
Manager
Manager
Joined: 29 Jun 2009
Affiliations: CFA Level 2 Candidate
Posts: 117
Own Kudos [?]: 1262 [0]
Given Kudos: 2
Concentration: Finance
Schools:RD 2: Darden Class of 2012
 Q49  V35
Send PM
Re: M25 - Question #10 [#permalink] New post   30 Oct 2009, 12:02
A doesn't necessarily need to hold true.

If your data contain all the same number your standard deviation would be 0 which is not a positive number.

In B we know that the standard deviation is = 0 (range is 0) and therefore it is not positive.
User avatar
lagomez
VP
VP
Joined: 05 Mar 2008
Posts: 1226
Own Kudos [?]: 518 [0]
Given Kudos: 31
Send PM
Re: M25 - Question #10 [#permalink] New post   31 Oct 2009, 17:52
we are never told how many numbers are contained in the set. The standard deviation is zero if there is one number or all the numbers are the same
User avatar
GMAT TIGER
VP
VP
Joined: 29 Aug 2007
Posts: 1021
Own Kudos [?]: 1726 [0]
Given Kudos: 19
Send PM
Re: M25 - Question #10 [#permalink] New post   02 Nov 2009, 22:29
stilite wrote:
Forgive me if I am wrong, but I truly believe the answer to this question to be "D."

The stimulus is asking:

Is the standard deviation of T positive?

Well,... stem question #1 clearly states that all elements of set T are positive. Thus, it is given that the ultimate standard deviation of set T is, in fact, positive.


Am I wrong?


1. Positive (+ve) elements (of the set) come in at least two flavors: (1, 1, 1, 1, 1, 1) or (2, 4, 5, 66, 77, 100).
In first case, SD is 0 where as in second case, SD is +ve. NSF.

2. Range is zero means, the elements of the set are same irrespective of signs. So SD is always 0. SUFF.
avatar
seluka
Intern
Intern
Joined: 12 Sep 2009
Posts: 10
Own Kudos [?]: 17 [0]
Given Kudos: 2
Send PM
Re: M25 - Question #10 [#permalink] New post   03 Nov 2009, 06:59
Per the OG, '0' is neither +ve nor -ve, how come 2 is sufficient? The questions is asking if the SD of T is +ve... Correct me if I'm wrong.
User avatar
lagomez
VP
VP
Joined: 05 Mar 2008
Posts: 1226
Own Kudos [?]: 518 [0]
Given Kudos: 31
Send PM
Re: M25 - Question #10 [#permalink] New post   03 Nov 2009, 08:16
seluka wrote:
Per the OG, '0' is neither +ve nor -ve, how come 2 is sufficient? The questions is asking if the SD of T is +ve... Correct me if I'm wrong.


The range is 0 therefore the SD is 0

0 is neither positive nor negative

The question is asking if the SD is positive...but as you said it's neither...so the answer is sufficient that the SD is not positive

It's a yes/no answer. In this case, no
User avatar
zaarathelab
Manager
Manager
Joined: 17 Aug 2009
Posts: 114
Own Kudos [?]: 1248 [3]
Given Kudos: 25
Send PM
Re: M25 - Question #10 [#permalink] New post   04 Nov 2009, 03:39
3
Kudos
Hi guys, the answer is definitely B

A gives 2 answers (As expressed in the solution) - set (6,6) will have range 0 (therefore not positive). Similarly, set (6,12) will have range 6 (positive)

Every set(excepting as set containing same numbers) will have a positive S.D.

The key to solving most gmatclub test questions is to pay attention to detail
User avatar
GMAT TIGER
VP
VP
Joined: 29 Aug 2007
Posts: 1021
Own Kudos [?]: 1726 [0]
Given Kudos: 19
Send PM
Re: M25 - Question #10 [#permalink] New post   04 Nov 2009, 21:19
+1 for Tip for the day:


zaarathelab wrote:
The key to solving most gmatclub test questions is to pay attention to detail


Archived Topic
Hi there,
Archived GMAT Club Tests question - no more replies possible.
Where to now? Try our up-to-date Free Adaptive GMAT Club Tests for the latest questions.
Still interested? Check out the "Best Topics" block above for better discussion and related questions.
Thank you for understanding, and happy exploring!
GMAT Club Bot
gmatclubot
Re: M25 - Question #10 [#permalink]
04 Nov 2009, 21:19
Moderator:
Bunuel
Math Expert
92901 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions