Author 
Message 
TAGS:

Hide Tags

Manager
Joined: 26 Mar 2007
Posts: 84
Concentration: General Management, Leadership

For a set X containing n integers, is the mean even? (1) n [#permalink]
Show Tags
09 Mar 2011, 10:15
3
This post received KUDOS
9
This post was BOOKMARKED
Question Stats:
46% (01:00) correct
54% (00:45) wrong based on 364 sessions
HideShow timer Statistics
For a set X containing n integers, is the mean even? (1) n is even. (2) All of the integers in set X are even. Best approach
Official Answer and Stats are available only to registered users. Register/ Login.



Director
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: 900

Re: Even Mean [#permalink]
Show Tags
09 Mar 2011, 10:31
This one is tricky. 1. Insufficient n = 2 X = {0,2} mean = 1. The answer is NO X = {3,5} mean = 4. The answer is YES 2. Insufficient X = {0,2} mean = 1. The answer is NO X = {2,2} mean = 2. The answer is YES 1) + 2) X = {0,2} mean = 1. The answer is NO X = {2,2} mean = 2. The answer is YES Hence E. kannn wrote: For a set X containing n integers, is the mean even? (1) n is even. (2) All of the integers in set X are even. Best approach
Last edited by gmat1220 on 09 Mar 2011, 10:32, edited 1 time in total.



Math Expert
Joined: 02 Sep 2009
Posts: 39673

For a set X containing n integers, is the mean even? (1) n [#permalink]
Show Tags
09 Mar 2011, 10:32
3
This post received KUDOS
Expert's post
3
This post was BOOKMARKED
kannn wrote: For a set X containing n integers, is the mean even? (1) n is even. (2) All of the integers in set X are even. Best approach For a set X containing n integers, is the mean even?The mean of a set = The sum of the elements / number of elements, so the question is whether mean=sum/n=even. (1) n is even > mean=sum/even. Not sufficient. (2) All of the integers in set X are even > so the sum of the elements is even > mean=even/n. Not sufficient. (1)+(2) The question becomes whether mean=even/even=even, which can not be determined as even/even could be even (for example 4/2=2=even), could be odd (for example 6/2=3=odd) or could be noninteger (for example 6/4=3/2). Not sufficient. Answer: E.
_________________
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? Extrahard Quant Tests with Brilliant Analytics



SVP
Joined: 16 Nov 2010
Posts: 1663
Location: United States (IN)
Concentration: Strategy, Technology

Re: Even Mean [#permalink]
Show Tags
09 Mar 2011, 21:55
From (1), 1,2 mean = 1.5 or 4,8 mean = 6, so (1) is not enough Again, 2,4 mean = 3 or 4,8 mean = 6, so (2) is not enough From (1) and (2), there is no definitive conclusion, so answer is E.
_________________
Formula of Life > Achievement/Potential = k * Happiness (where k is a constant)
GMAT Club Premium Membership  big benefits and savings



Director
Status: Tutor  BrushMyQuant
Joined: 05 Apr 2011
Posts: 619
Location: India
Concentration: Finance, Marketing
GMAT 1: 570 Q49 V19 GMAT 2: 700 Q51 V31
GPA: 3
WE: Information Technology (Computer Software)

Re: For a set X containing n integers, is the mean even? [#permalink]
Show Tags
10 Sep 2012, 06:05
1
This post received KUDOS
For a set X containing n integers, is the mean even? (1) n is even. (2) All of the integers in set X are even. Doesn't both the statements combined give an odd answer? Thus Statement (C) is correct but the MGMAT says that (E) is correct. Can someone explain the answer. take Set S as {2,4} then you will get the mean as 3 (odd) take Set S as {4,4,4,4} then you will get the mean as 4 (even) so answer will be E
_________________
Ankit
Check my Tutoring Site > Brush My Quant
GMAT Quant Tutor How to start GMAT preparations? How to Improve Quant Score? Gmatclub Topic Tags Check out my GMAT debrief
How to Solve : Statistics  Reflection of a line  Remainder Problems  Inequalities



Intern
Joined: 17 Mar 2011
Posts: 10
Schools: INSEAD, Booth, LBS
WE 1: Operations,
WE 2: IT Consulting, Hi Tech Project Management
WE 3: Baby Sitter

Re: For a set X containing n integers, is the mean even? [#permalink]
Show Tags
09 May 2014, 10:40
1
This post received KUDOS
Trick here is that integers in Set S is NOT UNIQUE EVEN INTEGER. Hence Ans. E. If integers were unique EVEN integers then Ans. would have been C.
_________________
The question isn’t who is going to let me; it’s who is going to stop me.



GMAT Club Legend
Joined: 09 Sep 2013
Posts: 15976

Re: For a set X containing n integers, is the mean even? (1) n [#permalink]
Show Tags
24 Jun 2014, 11:33
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
Joined: 09 Sep 2013
Posts: 15976

Re: For a set X containing n integers, is the mean even? (1) n [#permalink]
Show Tags
28 Aug 2015, 23:18
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



Senior Manager
Joined: 15 Sep 2011
Posts: 361
Location: United States
WE: Corporate Finance (Manufacturing)

For a set X containing n integers, is the mean even? (1) n [#permalink]
Show Tags
16 Sep 2015, 19:21
asif780 wrote: Trick here is that integers in Set S is NOT UNIQUE EVEN INTEGER. Hence Ans. E. If integers were unique EVEN integers then Ans. would have been C. Not true, for instance. If set {2,4}, then Avg. = 3 If set {2,6}, then Avg. = 4 Since both sets are unique even integers, the average can still be odd of even, and therefore whatever is above is not valid.



Manager
Joined: 05 Nov 2012
Posts: 56

Re: For a set X containing n integers, is the mean even? (1) n [#permalink]
Show Tags
03 Feb 2016, 02:34
Bunuel wrote: kannn wrote: For a set X containing n integers, is the mean even? (1) n is even. (2) All of the integers in set X are even. Best approach For a set X containing n integers, is the mean even?The mean of a set = The sum of the elements / number of elements, so the question is whether mean=sum/n=even. (1) n is even > mean=sum/even. Not sufficient. (2) All of the integers in set X are even > so the sum of the elements is even > mean=even/n. Not sufficient. (1)+(2) The question becomes whether mean=even/even=even, which can not be determined as even/even could be even (for example 4/2=2=even), could be odd (for example 6/2=3=odd) or could be noninteger (for example 6/4=3/2). Not sufficient. Answer: E. Hi Bunuel, I still do not understand how to solve these kind of questions methodically because everytime we have to consider cases I forget one or other cases to consider. So instead of trying numbers can you please describe a methodical approach to test this. For eg when we consider cases how many cases are possible and how to check against them. Such as we know that for the mean to be even the sum mandatorily has to be even however the base could be even or odd and can yield even or odd mean in both the cases i.e when N= even or when n=odd as non integers are also included.



Manager
Joined: 15 Jun 2016
Posts: 50
Location: India
Concentration: Technology, Strategy

Re: For a set X containing n integers, is the mean even? (1) n [#permalink]
Show Tags
08 Jul 2016, 22:40
One doubt  if the question had mentioned n positive integers, how does the answer varies ? My doubt is  whether the addition of "zero" to the set changes the even\odd nature of the mean ?



Senior Manager
Joined: 02 Mar 2012
Posts: 367

Re: For a set X containing n integers, is the mean even? (1) n [#permalink]
Show Tags
09 Jul 2016, 07:09
good question
take 2,4,6,8 and 4444 for both statements
and will come out to be E
hope it helps




Re: For a set X containing n integers, is the mean even? (1) n
[#permalink]
09 Jul 2016, 07:09







