Set A consists of all even integers between 2 and 100 : GMAT Problem Solving (PS)
Check GMAT Club App Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

It is currently 09 Dec 2016, 18:29
GMAT Club Tests

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.

Close

Request Expert Reply

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Set A consists of all even integers between 2 and 100

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

2 KUDOS received
Intern
Intern
avatar
Joined: 08 Mar 2011
Posts: 23
Followers: 0

Kudos [?]: 28 [2] , given: 31

Set A consists of all even integers between 2 and 100 [#permalink]

Show Tags

New post 14 Mar 2011, 08:20
2
This post received
KUDOS
11
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

65% (02:16) correct 35% (01:21) wrong based on 411 sessions

HideShow timer Statistics

Set A consists of all even integers between 2 and 100, inclusive. Set X is derived by reducing each term in set A by 50, set Y is derived by multiplying each term in set A by 1.5, and set Z is derived by dividing each term in set A by -4. Which of the following represents the ranking of the three sets in descending order of standard deviation?

(A) X, Y, Z
(B) X, Z, Y
(C) Y, Z, X
(D) Y, X, Z
(E) Z, Y, X
[Reveal] Spoiler: OA

Last edited by Bunuel on 17 Jul 2012, 02:34, edited 1 time in total.
Edited the OA.
Expert Post
5 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 35932
Followers: 6860

Kudos [?]: 90101 [5] , given: 10413

Re: std deviation [#permalink]

Show Tags

New post 14 Mar 2011, 09:12
5
This post received
KUDOS
Expert's post
4
This post was
BOOKMARKED
punyadeep wrote:
Set A consists of all even integers between 2 and 100, inclusive. Set X is derived by reducing each term in set A by 50, set Y is derived by multiplying each term in set A by 1.5, and set Z is derived by dividing each term in set A by -4. Which of the following represents the ranking of the three sets in descending order of standard deviation?
(A) X, Y, Z
(B) X, Z, Y
(C) Y, Z, X
(D) Y, X, Z
(E) Z, Y, X

pls explain the concept too....?? how do we find the spread frm mean when there r many terms involved..??


Set A - {2, 4, ..., 100};
Set X - {-48, -46, ..., 50};
Set Y - {3, 6, ..., 150};
Set Z - {-2/4, -4/4, ..., -100/4} = {-1/2, -1, -3/2, ..., -25}.

If we add or subtract a constant to each term in a set the SD will not change, so sets A and X will have the same SD.

If we increase or decrease each term in a set by the same percent (multiply by a constant) the SD will increase or decrease by the same percent, so set Y will have 1.5 times greater SD than set A and set Z will have 4 times less SD than set A (note SD can not be negative so SD of Z wil be SD of A divided by 4 not by -4).

So, the ranking of SD's in descending order is: Y, A=X, Z.

Answer: D.

Or the sane way as here: standard-deviation-110874.html#p890965

The standard deviation of a set shows how much variation there is from the mean, how widespread a given set is. So, a low standard deviation indicates that the data points tend to be very close to the mean, whereas high standard deviation indicates that the data are spread out over a large range of values.

You can see that set Y is most widespread and set Z is least widespread, so the correct answer is: Y, A=X, Z.

Answer: D.

For more on SD check:
math-standard-deviation-87905.html
ds-questions-about-standard-deviation-85896.html
ps-questions-about-standard-deviation-85897.html
_________________

New to the Math Forum?
Please read this: All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

SVP
SVP
avatar
Joined: 16 Nov 2010
Posts: 1672
Location: United States (IN)
Concentration: Strategy, Technology
Followers: 33

Kudos [?]: 507 [0], given: 36

Premium Member Reviews Badge
Re: std deviation [#permalink]

Show Tags

New post 14 Mar 2011, 18:28
The answer is D, I think the OA is wrongly posted as E.
_________________

Formula of Life -> Achievement/Potential = k * Happiness (where k is a constant)

GMAT Club Premium Membership - big benefits and savings

Manager
Manager
avatar
Joined: 05 Jul 2010
Posts: 204
Followers: 1

Kudos [?]: 18 [0], given: 18

Re: std deviation [#permalink]

Show Tags

New post 17 Apr 2011, 12:51
it is D. See Bunuel's explaination.
SVP
SVP
avatar
Joined: 16 Nov 2010
Posts: 1672
Location: United States (IN)
Concentration: Strategy, Technology
Followers: 33

Kudos [?]: 507 [0], given: 36

Premium Member Reviews Badge
Re: std deviation [#permalink]

Show Tags

New post 17 Apr 2011, 18:06
Answer is D - Y,X,Z

For X - SD remains unchanged

For Y - SD is multiplied by 1.5

For Z - SD is divided by -4

OA given is wrong.
_________________

Formula of Life -> Achievement/Potential = k * Happiness (where k is a constant)

GMAT Club Premium Membership - big benefits and savings

Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 35932
Followers: 6860

Kudos [?]: 90101 [0], given: 10413

Re: Set A consists of all even integers between 2 and 100 [#permalink]

Show Tags

New post 12 Jul 2013, 01:35
GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 09 Sep 2013
Posts: 12904
Followers: 562

Kudos [?]: 158 [0], given: 0

Premium Member
Re: Set A consists of all even integers between 2 and 100 [#permalink]

Show Tags

New post 09 Aug 2014, 20:00
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Manager
Manager
avatar
Joined: 18 Jul 2013
Posts: 54
Followers: 0

Kudos [?]: 5 [0], given: 151

Re: Set A consists of all even integers between 2 and 100 [#permalink]

Show Tags

New post 20 Aug 2014, 15:18
1
This post was
BOOKMARKED
Hi Bunnel,

Here in the question the arrangement asked is in descending order then why answer is D.

D option's arrangement is in ascending order isn't it.
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 35932
Followers: 6860

Kudos [?]: 90101 [0], given: 10413

Re: Set A consists of all even integers between 2 and 100 [#permalink]

Show Tags

New post 21 Aug 2014, 03:00
Manager
Manager
avatar
Joined: 18 Jul 2013
Posts: 54
Followers: 0

Kudos [?]: 5 [0], given: 151

Re: Set A consists of all even integers between 2 and 100 [#permalink]

Show Tags

New post 21 Aug 2014, 08:17
Hi Bunnel,

Thanks for the reply, i realized now it should be greater to smaller. Got confused, now it is clear.
GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 09 Sep 2013
Posts: 12904
Followers: 562

Kudos [?]: 158 [0], given: 0

Premium Member
Re: Set A consists of all even integers between 2 and 100 [#permalink]

Show Tags

New post 27 Aug 2015, 10:53
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 09 Sep 2013
Posts: 12904
Followers: 562

Kudos [?]: 158 [0], given: 0

Premium Member
Re: Set A consists of all even integers between 2 and 100 [#permalink]

Show Tags

New post 01 Dec 2016, 14:55
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Intern
Intern
User avatar
Joined: 11 Jan 2016
Posts: 36
Followers: 0

Kudos [?]: 1 [0], given: 32

Re: Set A consists of all even integers between 2 and 100 [#permalink]

Show Tags

New post 02 Dec 2016, 04:02
So division (as in dividing every term in the set by the same number) makes the SD smaller, correct?

I understand the problem and what concepts apply but was lost when it came to division and SD.
Re: Set A consists of all even integers between 2 and 100   [#permalink] 02 Dec 2016, 04:02
    Similar topics Author Replies Last post
Similar
Topics:
3 Set A consists of 2 positive integers, and set B consists GMATPrepNow 4 01 Nov 2016, 07:03
Experts publish their posts in the topic Set A contains all the even numbers between 2 and 50 inclusive. Set B Bunuel 1 14 Feb 2016, 04:40
11 Experts publish their posts in the topic If 3^k is a divisor of the product of all even integers between 2 TeamGMATIFY 3 07 Feb 2016, 17:08
24 Set A consists of all the integers between 10 and 21, inclus daviesj 26 28 Dec 2012, 06:18
10 Experts publish their posts in the topic Set A consists of all prime numbers between 10 and 25; Set B punyadeep 14 14 Mar 2011, 08:05
Display posts from previous: Sort by

Set A consists of all even integers between 2 and 100

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| 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®.