GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

It is currently 03 Aug 2020, 04:22

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

Set A consists of all prime numbers between 10 and 25; Set B

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

Hide Tags

Find Similar Topics 
Intern
Intern
avatar
Joined: 08 Mar 2011
Posts: 15
Set A consists of all prime numbers between 10 and 25; Set B  [#permalink]

Show Tags

New post Updated on: 16 Jun 2013, 10:46
2
10
00:00
A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

67% (01:42) correct 33% (01:53) wrong based on 472 sessions

HideShow timer Statistics

Set A consists of all prime numbers between 10 and 25; Set B consists of consecutive even integers, and set C consists of consecutive multiples of 7. If all the three sets have an equal number of terms, which of the following represents the ranking of these sets in an ascending order of the standard deviation?

(A) C, A, B
(B) A, B, C
(C) C, B, A
(D) B, C, A
(E) B, A, C

Originally posted by punyadeep on 14 Mar 2011, 08:05.
Last edited by Bunuel on 16 Jun 2013, 10:46, edited 1 time in total.
OA added.
Most Helpful Expert Reply
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 65761
Re: standard deviation  [#permalink]

Show Tags

New post 14 Mar 2011, 08:43
5
4
punyadeep wrote:
Set A consists of all prime numbers between 10 and 25; Set B consists of consecutive even integers, and set C consists of consecutive multiples of 7. If all the three sets have an equal number of terms, which of the following represents the ranking of these sets in an ascending order of the standard deviation?

(A) C, A, B
(B) A, B, C
(C) C, B, A
(D) B, C, A
(E) B, A, C


Set A - {11, 13, 17, 19, 23};
Set B - {5 consecutive even integers}, for example - {12, 14, 16, 18, 20};
Set C - {5 consecutive multiples of 7}, for example - {7, 14, 21, 28, 35}.

Now, 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 C is most widespread and set B is least widespread, so the correct answer is: B, A, C.

Answer: E.
_________________
General Discussion
Intern
Intern
avatar
Joined: 08 Mar 2011
Posts: 15
Re: standard deviation  [#permalink]

Show Tags

New post 14 Mar 2011, 08:59
thnx so much..........oa is incorrect then...!!
Retired Moderator
avatar
B
Joined: 16 Nov 2010
Posts: 1162
Location: United States (IN)
Concentration: Strategy, Technology
Reviews Badge
Re: standard deviation  [#permalink]

Show Tags

New post 14 Mar 2011, 18:37
A-> 11,13,17,19,23

B-> 0,2,4,6,8

C -> 7,14,21,28,35

So the answer is E, as C hax maximum gap between elements, and A has slightly more than B because of the last number - 23.

The OA seems to be wrong. Just curious to know where is this question from; I've seen two SD questions with wrong OA now.
_________________
Formula of Life -> Achievement/Potential = k * Happiness (where k is a constant)

GMAT Club Premium Membership - big benefits and savings
Intern
Intern
avatar
Joined: 08 Mar 2011
Posts: 15
Re: standard deviation  [#permalink]

Show Tags

New post 14 Mar 2011, 18:45
the question is from 700-800 level questions.........however there is no source,,,if u wish i can upload the document cos i find this document very good...!!!
Director
Director
avatar
Status: Impossible is not a fact. It's an opinion. It's a dare. Impossible is nothing.
Affiliations: University of Chicago Booth School of Business
Joined: 03 Feb 2011
Posts: 611
Reviews Badge
Re: standard deviation  [#permalink]

Show Tags

New post 15 Mar 2011, 06:10
SD will be high if the sample is not compact since SD is a measure of compactness.

Mean will fall in the middle of the highest and lowest. So more the distance from the mean - the higher the SD. Assuming all the data is positive the SD will be proportional to the range (highest - smallest)

Set A {11 13 17 19 23} range = 12
Se B {12 14 16 18 20} range = 8
Set C {14 21 28 35 42 } range = 28

SD(B) < SD(A) < SD(C)

Please correct me if this reasoning is wrong.
Senior Manager
Senior Manager
avatar
Status: Up again.
Joined: 31 Oct 2010
Posts: 448
Concentration: Strategy, Operations
GMAT 1: 710 Q48 V40
GMAT 2: 740 Q49 V42
Re: standard deviation  [#permalink]

Show Tags

New post 15 Mar 2011, 09:19
punyadeep wrote:
the question is from 700-800 level questions.........however there is no source,,,if u wish i can upload the document cos i find this document very good...!!!


Just my 2 cents: there are a lot of "good" documents around.. but least we can do is be careful on our part. If others didnt testify the right answer, I would have missed my dinner!

Edit: I just found out, this question is from Veritas Prep "Statistics and Problem Solving" book and the OA is indeed E.
_________________
My GMAT debrief: http://gmatclub.com/forum/from-620-to-710-my-gmat-journey-114437.html
Retired Moderator
avatar
Joined: 20 Dec 2010
Posts: 1462
Re: standard deviation  [#permalink]

Show Tags

New post 15 Mar 2011, 09:27
punyadeep wrote:
the question is from 700-800 level questions.........however there is no source,,,if u wish i can upload the document cos i find this document very good...!!!


Please do so. thanks.
Intern
Intern
avatar
Joined: 08 Mar 2011
Posts: 15
Re: standard deviation  [#permalink]

Show Tags

New post 16 Mar 2011, 05:45
4
@ fluke...two documents iam uploading......they were sent to me by a frnd who scored 750 and he just went through this document for quant twice.......i found it focussed and helpful too...!!
Attachments

File comment: quant 700-800
Quant 700 to 800 level questions.pdf [1 MiB]
Downloaded 6830 times

To download please login or register as a user

Intern
Intern
avatar
Joined: 08 Mar 2011
Posts: 15
Re: standard deviation  [#permalink]

Show Tags

New post 16 Mar 2011, 05:48
2
@ fluke...here r the answwers to it...!!
Attachments

File comment: answers with detailed explanations
BIBLE SOLUTIONS.pdf [1.95 MiB]
Downloaded 2698 times

To download please login or register as a user

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 65761
Re: Set A consists of all prime numbers between 10 and 25; Set B  [#permalink]

Show Tags

New post 12 Jul 2013, 01:35
Verbal Forum Moderator
User avatar
B
Joined: 10 Oct 2012
Posts: 562
Re: Set A consists of all prime numbers between 10 and 25; Set B  [#permalink]

Show Tags

New post Updated on: 12 Jul 2013, 12:03
punyadeep wrote:
Set A consists of all prime numbers between 10 and 25; Set B consists of consecutive even integers, and set C consists of consecutive multiples of 7. If all the three sets have an equal number of terms, which of the following represents the ranking of these sets in an ascending order of the standard deviation?

(A) C, A, B
(B) A, B, C
(C) C, B, A
(D) B, C, A
(E) B, A, C


Set A \(\to {11,13,17,19,23}\)

Fact: Addition/subtraction of any number from a given set doesn't change the S.D of the given set.

From Set A, subtract 11 across to represent \(Set A^'\) as \(\to {0,2,6,8,12}\). \(S.D of Set A = S.D of Set A^'\)

If you notice closely, Set \(A^'\) is very close to Set B, just that Set B looks like \(\to{0,2,4,6,8}\),i.e. a data-point of 12 is present instead of 4, which makes \(Set A^'\) more spread-out then Set B.

Thus, \(S.D of Set B< S.D of Set A^'\)

Assume Set C\(\to {0,7,14,21,28}\)

S.D represents how far are the data points are from the mean of the set, we can see that Set C has the most spread-out data points and the correct order = B,A,C.

E.
_________________

Originally posted by mau5 on 12 Jul 2013, 09:28.
Last edited by mau5 on 12 Jul 2013, 12:03, edited 1 time in total.
Director
Director
User avatar
Joined: 14 Dec 2012
Posts: 670
Location: India
Concentration: General Management, Operations
GMAT 1: 700 Q50 V34
GPA: 3.6
GMAT ToolKit User
Re: Set A consists of all prime numbers between 10 and 25; Set B  [#permalink]

Show Tags

New post 12 Jul 2013, 09:47
1
punyadeep wrote:
Set A consists of all prime numbers between 10 and 25; Set B consists of consecutive even integers, and set C consists of consecutive multiples of 7. If all the three sets have an equal number of terms, which of the following represents the ranking of these sets in an ascending order of the standard deviation?

(A) C, A, B
(B) A, B, C
(C) C, B, A
(D) B, C, A
(E) B, A, C


Hi,

few things to keep in mind.
=>std deviation depends on distance of each term from mean and number of terms.==>since number of terms are same..we are concerned only about distance of EACH TERM from MEAN.==more the distance more the deviation.
=>std deviation is always positive==>so not concerned whether numbers are positive or negative.

SET A==>(11,13,17,19,23)==>avg around 16==>you can see distance of 11,13,17,19,23 is 5,3,1,3,7....1)
SET B==>(CONSECUTIVE EVEN INTEGERS...)= ( N-4,N-2,N,N+2,N+4)===>mean=N==>DISTANCE FROM MEAN= 4,2,0,2,4
SET C==>MULTIPLES OF 7 ====N-14,N-7,N,N+7,N+14===>MEAN=N====>DISTANCE FROM MEAN=14,7,0,7,14.

if we compare all distance clearly we can say B<A<C===>HENCE OPTION E
_________________
When you want to succeed as bad as you want to breathe ...then you will be successfull....

GIVE VALUE TO OFFICIAL QUESTIONS...



GMAT RCs VOCABULARY LIST: http://gmatclub.com/forum/vocabulary-list-for-gmat-reading-comprehension-155228.html
learn AWA writing techniques while watching video : http://www.gmatprepnow.com/module/gmat-analytical-writing-assessment
: http://www.youtube.com/watch?v=APt9ITygGss
Intern
Intern
avatar
Joined: 09 Dec 2014
Posts: 43
GMAT 1: 600 Q42 V32
GMAT 2: 710 Q48 V38
GPA: 3.7
Reviews Badge
Re: Set A consists of all prime numbers between 10 and 25; Set B  [#permalink]

Show Tags

New post 29 Dec 2015, 23:24
gmat1220 wrote:
SD will be high if the sample is not compact since SD is a measure of compactness.

Mean will fall in the middle of the highest and lowest. So more the distance from the mean - the higher the SD. Assuming all the data is positive the SD will be proportional to the range (highest - smallest)

Set A {11 13 17 19 23} range = 12
Se B {12 14 16 18 20} range = 8
Set C {14 21 28 35 42 } range = 28

SD(B) < SD(A) < SD(C)

Please correct me if this reasoning is wrong.


Buneal, please could you provide more info on how the standard deviation is proportional to the range. Is this strategy useful when you are in stressed conditions?

Thanks in Advance
Manager
Manager
User avatar
B
Joined: 01 Apr 2020
Posts: 82
Location: India
CAT Tests
Re: Set A consists of all prime numbers between 10 and 25; Set B  [#permalink]

Show Tags

New post 18 Jun 2020, 05:25
Bunuel wrote:
punyadeep wrote:
Set A consists of all prime numbers between 10 and 25; Set B consists of consecutive even integers, and set C consists of consecutive multiples of 7. If all the three sets have an equal number of terms, which of the following represents the ranking of these sets in an ascending order of the standard deviation?

(A) C, A, B
(B) A, B, C
(C) C, B, A
(D) B, C, A
(E) B, A, C


Set A - {11, 13, 17, 19, 23};
Set B - {5 consecutive even integers}, for example - {12, 14, 16, 18, 20};
Set C - {5 consecutive multiples of 7}, for example - {7, 14, 21, 28, 35}.

Now, 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 C is most widespread and set B is least widespread, so the correct answer is: B, A, C.

Answer: E.


Great explanation...
But you don't even have to list them out..

we know that each prime number greater than 3 can be expressed in the form 6n + 1 or 6n - 1
Clearly the difference will be less than 7

and talking about A, the difference will be 2 units.

Therefore C is our winner, followed by B and then A.
GMAT Club Bot
Re: Set A consists of all prime numbers between 10 and 25; Set B   [#permalink] 18 Jun 2020, 05:25

Set A consists of all prime numbers between 10 and 25; Set B

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





cron

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne