GMAT Changed on April 16th - Read about the latest changes here

It is currently 21 Apr 2018, 19:52

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

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Is the standard deviation of Set A greater than or equal to the standa

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

Hide Tags

Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 44599
Is the standard deviation of Set A greater than or equal to the standa [#permalink]

Show Tags

New post 11 Apr 2018, 21:23
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

64% (00:44) correct 36% (00:47) wrong based on 11 sessions

HideShow timer Statistics

Is the standard deviation of Set A greater than or equal to the standard deviation of Set B?

(1) Set B can be formed by dividing each value in Set A by 4.

(2) Set A consists of 7 unique numbers.
[Reveal] Spoiler: OA

_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | 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

Expert Post
SVP
SVP
User avatar
P
Joined: 08 Jul 2010
Posts: 2066
Location: India
GMAT: INSIGHT
WE: Education (Education)
Reviews Badge
Is the standard deviation of Set A greater than or equal to the standa [#permalink]

Show Tags

New post 12 Apr 2018, 06:06
Expert's post
1
This post was
BOOKMARKED
Bunuel wrote:
Is the standard deviation of Set A greater than or equal to the standard deviation of Set B?

(1) Set B can be formed by dividing each value in Set A by 4.

(2) Set A consists of 7 unique numbers.


Question : Is Standard Deviation of A > Standard deviation of B?

Statement 1: Set B can be formed by dividing each value in Set A by 4.

Since each value of A is divided by 4 to obtain each value of Set B therefore the gaps among the values will also be divided by 4 hence standard deviation will decrease hence

Standard Deviation of A > Standard deviation of B

SUFFICIENT

Statement 2: Set A consists of 7 unique numbers

No Information of Set B hence

NOT SUFFICIENT

Answer: option A


CONCEPT TABLE ON STANDARD DEVIATION

STANDARD DEVIATION
Standard Deviation : Average Deviation of Terms of a set from the Mean value of the Set
1) If we had assumed that all barrels had the same amount of mixture then standard deviation would have been zero. Non Zero standard deviation means that all barrels don't have the same amount of Mixture and the the size of Barrels doesn't matter, all that matters is the amount of Mixture in the barrels

2) The standard deviation of a set doesn't change if a constant is added to/subtracted from each terms of the set
e.g.{1, 2, 3, 4, 5} will have same standard Deviation as {1+10, 2+10, 3+10, 4+10, 5+10}
Reason: The deviation remains same as before if the constant is added to/Subtracted from each term

3) Standard Deviation of the Set changes when a constant term which is not equal to 1 is multiplied with/divides every terms of the set
e.g. {0.7, 1.4, 2.1, 2.8, 3.5} will have Standard Deviation = 0.7* Standard deviation of set {1, 2, 3, 4, 5}
Reason: The deviation gets multiplied by or divided by the same constant that every terms is multiplied or divided with
_________________

Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION

Intern
Intern
avatar
B
Joined: 28 Apr 2014
Posts: 49
GMAT ToolKit User
Re: Is the standard deviation of Set A greater than or equal to the standa [#permalink]

Show Tags

New post 12 Apr 2018, 07:51
IMO A

St1 implies that sd in b will decrease compared to A as every term is divided by 4
St2 can't say anything about sd
Intern
Intern
avatar
B
Joined: 28 Aug 2016
Posts: 5
CAT Tests
Re: Is the standard deviation of Set A greater than or equal to the standa [#permalink]

Show Tags

New post 13 Apr 2018, 12:45
uhm no - the answer is C.

Even if all the values in B are 4 times the value in A, if they are all the same - meaning not unique then both sets have SDs of 0.
Re: Is the standard deviation of Set A greater than or equal to the standa   [#permalink] 13 Apr 2018, 12:45
Display posts from previous: Sort by

Is the standard deviation of Set A greater than or equal to the standa

  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 | Emoji artwork provided by EmojiOne

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®.