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

It is currently 17 Sep 2014, 21:43

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

You make a new sequence by removing 2 elements from the

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Director
Director
avatar
Joined: 14 Sep 2005
Posts: 998
Location: South Korea
Followers: 2

Kudos [?]: 31 [0], given: 0

GMAT Tests User
You make a new sequence by removing 2 elements from the [#permalink] New post 24 Nov 2005, 04:38
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
You make a new sequence by removing 2 elements from the sequence {1, 3, 5, 7, 9, 11, 13, 15, 17, 19}. What is the standard deviation of the new sequence?

(1) The median of the new sequence is 10.
(2) The new sequence has the same average as the original sequence.
_________________

Auge um Auge, Zahn um Zahn :twisted: !

SVP
SVP
User avatar
Joined: 05 Apr 2005
Posts: 1736
Followers: 3

Kudos [?]: 33 [0], given: 0

GMAT Tests User
Re: DS - Standard deviation [#permalink] New post 24 Nov 2005, 07:22
E.

from i, sequuences {1, 3, 5, 7, 13, 15, 17, 19} and {3, 5, 7, 9, 11, 13, 15, 17}, both, have median 10 but they have different SDs.

from ii, sequuences {1, 3, 5, 7, 13, 15, 17, 19} and {3, 5, 7, 9, 11, 13, 15, 17}, both, have the same mean 10 as the original has but their SDs are different.

from i and ii also the have different SDs with same mean and median.
Director
Director
avatar
Joined: 27 Jun 2005
Posts: 517
Location: MS
Followers: 2

Kudos [?]: 11 [0], given: 0

GMAT Tests User
Re: DS - Standard deviation [#permalink] New post 24 Nov 2005, 23:42
HIMALAYA wrote:
E.

from i, sequuences {1, 3, 5, 7, 13, 15, 17, 19} and {3, 5, 7, 9, 11, 13, 15, 17}, both, have median 10 but they have different SDs.

from ii, sequuences {1, 3, 5, 7, 13, 15, 17, 19} and {3, 5, 7, 9, 11, 13, 15, 17}, both, have the same mean 10 as the original has but their SDs are different.

from i and ii also the have different SDs with same mean and median.


HIMALAYA...
can you pls explain ..how you concluded that these different sets will have different SD..:roll: :roll: .....any trick or just observation ...
SVP
SVP
User avatar
Joined: 24 Sep 2005
Posts: 1898
Followers: 10

Kudos [?]: 104 [0], given: 0

GMAT Tests User
Re: DS - Standard deviation [#permalink] New post 10 Jun 2006, 19:35
gamjatang wrote:
You make a new sequence by removing 2 elements from the sequence {1, 3, 5, 7, 9, 11, 13, 15, 17, 19}. What is the standard deviation of the new sequence?

(1) The median of the new sequence is 10.
(2) The new sequence has the same average as the original sequence.


Pick E in this one.
(1) in order to maintain the median of 10, we have several cases:
Keep (9,11) , we can remove any number of the rest : one number in the left side of (9,11) and another in the right side of (9,11).
For example: remove 1 and 19 ...then compare with removal of (3,19). The two standard deviations are different ---> that means we can't have exactly the same SD for all removals ---> can't find such SD --> insuff

(2) this statement means: the two removed numbers have a sum which is equal to mean*2 . The mean here is 10 . Thus, the pairs of removal can be either ( 1,19) , (3,17) , (5,15) , (3,13) , (9,11) . Since the mean is unchanged, the removal of (1,19) yields a smaller SD than that of (3,13) because (1,19) has wider distances to the mean than (3,13) does. --> no common SD for all removal --> insuff
Re: DS - Standard deviation   [#permalink] 10 Jun 2006, 19:35
    Similar topics Author Replies Last post
Similar
Topics:
If two numbers are removed from 2, 4, 6, 8, 10, 12, 14, 16, arjtryarjtry 6 04 Sep 2008, 02:37
If two numbers are removed from 2, 4, 6, 8, 10, 12, 14, 16, arjtryarjtry 4 28 Jul 2008, 18:58
Are all elements of an increasing infinite sequence of marcodonzelli 2 08 Mar 2008, 05:44
There is an finite number of elements in a sequence. What is gamjatang 10 26 Nov 2005, 06:38
sequence S = { 2, 4, 6, ..., 24 } You make sequence M by gamjatang 4 24 Nov 2005, 06:29
Display posts from previous: Sort by

You make a new sequence by removing 2 elements from the

  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®.