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

 It is currently 27 Mar 2015, 18:01

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# The set S of numbers has the following properties: I) If x

Author Message
TAGS:
Manager
Joined: 22 Feb 2007
Posts: 69
Followers: 1

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

The set S of numbers has the following properties: I) If x [#permalink]  28 Feb 2007, 17:57
00:00

Difficulty:

(N/A)

Question Stats:

20% (01:02) correct 80% (01:29) wrong based on 6 sessions
The set S of numbers has the following properties:

I) If x is in S, then 1/x is in S.
II) If both x and y are in S, then so is x + y.

Is 3 in S?

(1) 1/3 is in S.
(2) 1 is in S.
Manager
Joined: 04 Oct 2006
Posts: 189
Followers: 1

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

I get A as well.

If 1/3 is in S, the 1 / 1/3, or 3, is also in S

Having 1 be in S says nothing about 3
_________________

wall street...bulls, bears, people from connecticut

Manager
Joined: 22 Feb 2007
Posts: 69
Followers: 1

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

I too thought it was A but with a confusing explanation is mentioned as D

Consider (1) alone. Since 1/3 is in S, we know from Property I that 1/(1/3) = 3 is in S. Hence, (1) is sufficient.
Consider (2) alone. Since 1 is in S, we know from Property II that 1 + 1 = 2 (Note, nothing in Property II prevents x and y from standing for the same number. In this case both stand for 1.) is in S. Applying Property II again shows that 1 + 2 = 3 is in S. Hence, (2) is also sufficient. The answer is D.
Current Student
Joined: 28 Dec 2004
Posts: 3392
Location: New York City
Schools: Wharton'11 HBS'12
Followers: 13

Kudos [?]: 180 [0], given: 2

statement 2 says

that if 1 is in the set then 1/1 is in the set..i.e x=1, then say y=1 also,..which means 2 is in the set..

taking both statements, if 1/x,x and y are in the set then 3 is also in the set...

statement 2 is sufficient
Senior Manager
Joined: 29 Jan 2007
Posts: 450
Location: Earth
Followers: 2

Kudos [?]: 40 [0], given: 0

One cant win with these DS crap...u always miss some angle..I guess PRACTICE is the key. Good catch guys...I tend to agree its (D)...unless somepne pulls something totally different
Senior Manager
Joined: 18 Feb 2007
Posts: 253
Followers: 1

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

yep you are right..D

wow, good DS problem!
Intern
Joined: 10 Jun 2009
Posts: 31
Location: Stockholm, Sweden
Followers: 0

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

Re: DS - number properties [#permalink]  16 Jun 2009, 04:24
I dont think this problem is confusing at all.

1) If 1/3 is in the set then 1 must also be in the set and then 3 must also be in the set
2) If 1 is in the set then 3 must also be in the set

For those of you answering A, try do first look at the second statement and solve it without knowing that the first statement says.
Current Student
Joined: 12 Jun 2009
Posts: 1847
Location: United States (NC)
Concentration: Strategy, Finance
Schools: UNC (Kenan-Flagler) - Class of 2013
GMAT 1: 720 Q49 V39
WE: Programming (Computer Software)
Followers: 22

Kudos [?]: 208 [0], given: 52

Re: DS - number properties [#permalink]  16 Jun 2009, 07:39
yeah i got D as well. I thought of A right away as many others did but then thought to myself "this question must be "difficult" "so i looked at 2 closely and got D. Since most are doing computer test we can probably gauge how difficult problems become and hopefully not jump to conclusions so quickly.
_________________

VP
Joined: 05 Jul 2008
Posts: 1433
Followers: 35

Kudos [?]: 251 [0], given: 1

Re: DS - number properties [#permalink]  18 Jun 2009, 08:36
shaselai wrote:
yeah i got D as well. I thought of A right away as many others did but then thought to myself "this question must be "difficult" "so i looked at 2 closely and got D. Since most are doing computer test we can probably gauge how difficult problems become and hopefully not jump to conclusions so quickly.

Sorry But where does the Q say that X and Y are different/same. It does say that if X and Y are in the set, X + Y is also in the set

Just because X and Y are different letters does not mean they have different values, X can be equal to Y.

Or they could be very well the same

It is very well possible that the same 1 can refer to X and Y be 4

I mean 1 is in S, then 1/1 is also in S. With a single 1, we can satisfy the statement (1). We dont need another 1 to satisfy the statement 1.

The set does not need to have more than 1 number. Consider the set {1},

Statement 1 is good, 1 is in Set S, 1/1 is also in the Set. We dont need to satisfy statement 2 as Set S does not have two numbers.

Am I just hallucinating or Do I have a point in saying that x and 1/x could very well be the same one?
Intern
Joined: 07 Jan 2005
Posts: 8
Location: New York
Followers: 0

Kudos [?]: 2 [0], given: 0

Re: DS - number properties [#permalink]  23 Aug 2009, 08:49
X and Y could be the same value but that doesn't take away the solution.

Statement 1 confirms that 3 is in the set as 1/x of 1/3 = 3
Statement 2 says 1 is in set S . Applying the fact that if both x and y are in S , then so is x+y.
Taking x = y = 1 , leads to x+y=2 is in S , further down , x=1,y=2 leads to x+y=3 .

Hence D.

icandy wrote:
shaselai wrote:
yeah i got D as well. I thought of A right away as many others did but then thought to myself "this question must be "difficult" "so i looked at 2 closely and got D. Since most are doing computer test we can probably gauge how difficult problems become and hopefully not jump to conclusions so quickly.

Sorry But where does the Q say that X and Y are different/same. It does say that if X and Y are in the set, X + Y is also in the set

Just because X and Y are different letters does not mean they have different values, X can be equal to Y.

Or they could be very well the same

It is very well possible that the same 1 can refer to X and Y be 4

I mean 1 is in S, then 1/1 is also in S. With a single 1, we can satisfy the statement (1). We dont need another 1 to satisfy the statement 1.

The set does not need to have more than 1 number. Consider the set {1},

Statement 1 is good, 1 is in Set S, 1/1 is also in the Set. We dont need to satisfy statement 2 as Set S does not have two numbers.

Am I just hallucinating or Do I have a point in saying that x and 1/x could very well be the same one?
Manager
Joined: 14 Aug 2009
Posts: 123
Followers: 2

Kudos [?]: 94 [2] , given: 13

Re: DS - number properties [#permalink]  23 Aug 2009, 18:50
2
KUDOS
S is a set!!!

and "set" can't have duplication values!

therefore there is only one "1" in S.

_________________

Kudos me if my reply helps!

Last edited by flyingbunny on 24 Aug 2009, 05:46, edited 1 time in total.
Manager
Joined: 13 Jan 2009
Posts: 172
Followers: 4

Kudos [?]: 17 [0], given: 9

Re: DS - number properties [#permalink]  24 Aug 2009, 05:27
I am still going with A
Manager
Joined: 10 Aug 2009
Posts: 130
Followers: 3

Kudos [?]: 57 [0], given: 10

Re: DS - number properties [#permalink]  24 Aug 2009, 06:46
There is a set of numbers S with n elements in it. A letter is assigned to each number.
let x=1.
By the property of the set, there should be another element y=1/x=1. It is possible for two elements in the multiset (see note) to be same. Using the first property of the set and one element of that set x=1, we can conclude that S=(1,1,....).
Now using the second property, there should be z=x+y=2 and there should be 1/z (but we do not need this one to answer the question). If z=2, there should be c=z+x=2+1=3 and there should be d=z+y=1+2=3...S=(1,1,2,3,3,...) ..

Note: If S is a set, then all elements should be different. But if S is a multiset , elements are not required to be different. My solution is based on the assumption that s is a multiset...and one element can be repeated more than once...I think the auther of the question had a multiset in mind (just based on the correct answer).

Last edited by LenaA on 24 Aug 2009, 07:06, edited 1 time in total.
Manager
Joined: 14 Aug 2009
Posts: 123
Followers: 2

Kudos [?]: 94 [1] , given: 13

Re: DS - number properties [#permalink]  24 Aug 2009, 06:56
1
KUDOS
LenaA wrote:
I think it should be D because statement 2 is sufficient.
There is a set of numbers S with n elements in it. A letter is assigned to each number.
let x=1.
By the property of the set, there should be another element y=1/x=1. It is possible for two elements in the set to be same. Using the first property of the set and one element of that set x=1, we can conclude that S=(1,1,....).
Now using the second property, there should be z=x+y=2 and there should be 1/z (but we do not need this one to answer the question). If z=2, there should be c=z+x=2+1=3 and there should be d=z+y=1+2=3...S=(1,1,2,3,3,...) ..

It is not possible.
Please check the definition of "set".
_________________

Kudos me if my reply helps!

Manager
Joined: 10 Aug 2009
Posts: 130
Followers: 3

Kudos [?]: 57 [0], given: 10

Re: DS - number properties [#permalink]  24 Aug 2009, 07:11
flyingbunny wrote:
LenaA wrote:
I think it should be D because statement 2 is sufficient.
There is a set of numbers S with n elements in it. A letter is assigned to each number.
let x=1.
By the property of the set, there should be another element y=1/x=1. It is possible for two elements in the set to be same. Using the first property of the set and one element of that set x=1, we can conclude that S=(1,1,....).
Now using the second property, there should be z=x+y=2 and there should be 1/z (but we do not need this one to answer the question). If z=2, there should be c=z+x=2+1=3 and there should be d=z+y=1+2=3...S=(1,1,2,3,3,...) ..

It is not possible.
Please check the definition of "set".

It is a very good point, but set S can be a multiset...it is obvious that the auther had a multiset in mind based on the correct solution D....My initial answer though was A...i am not sure the question is phrased well. We should be given if it is possible to have 2 same elements.
Intern
Joined: 30 Jun 2009
Posts: 48
Followers: 1

Kudos [?]: 9 [0], given: 2

Re: DS - number properties [#permalink]  25 Aug 2009, 06:26
I am with A.

Manager
Joined: 10 Aug 2009
Posts: 130
Followers: 3

Kudos [?]: 57 [0], given: 10

Re: DS - number properties [#permalink]  25 Aug 2009, 09:11
defoue wrote:
I am with A.

amd08 posted the question and she/he says that it's D. She/he also gives the original explanation...see at the beginning of this thread amd08's posts

Last edited by LenaA on 25 Aug 2009, 09:56, edited 1 time in total.
Senior Manager
Joined: 27 May 2009
Posts: 282
Followers: 2

Kudos [?]: 104 [0], given: 18

Re: [#permalink]  25 Aug 2009, 09:38
amd08 wrote:
I too thought it was A but with a confusing explanation is mentioned as D

Consider (1) alone. Since 1/3 is in S, we know from Property I that 1/(1/3) = 3 is in S. Hence, (1) is sufficient.
Consider (2) alone. Since 1 is in S, we know from Property II that 1 + 1 = 2 (Note, nothing in Property II prevents x and y from standing for the same number. In this case both stand for 1.) is in S. Applying Property II again shows that 1 + 2 = 3 is in S. Hence, (2) is also sufficient. The answer is D.

This way S will have infinite values...... or hence any no can be in S... I dont think this is worth enough.. What is the source of this ques
Manager
Joined: 22 Sep 2009
Posts: 222
Location: Tokyo, Japan
Followers: 2

Kudos [?]: 18 [0], given: 8

Re: Re: [#permalink]  23 Nov 2009, 04:37
rohansherry wrote:
amd08 wrote:
I too thought it was A but with a confusing explanation is mentioned as D

Consider (1) alone. Since 1/3 is in S, we know from Property I that 1/(1/3) = 3 is in S. Hence, (1) is sufficient.
Consider (2) alone. Since 1 is in S, we know from Property II that 1 + 1 = 2 (Note, nothing in Property II prevents x and y from standing for the same number. In this case both stand for 1.) is in S. Applying Property II again shows that 1 + 2 = 3 is in S. Hence, (2) is also sufficient. The answer is D.

This way S will have infinite values...... or hence any no can be in S... I dont think this is worth enough.. What is the source of this ques

This is true... if this was intended then any no. given in set S will result in the answer being D
Re: Re:   [#permalink] 23 Nov 2009, 04:37
Similar topics Replies Last post
Similar
Topics:
1 The set S of numbers has the following properties: I) If x 6 09 Jun 2010, 05:51
The set S of numbers has the following properities: I) If x 10 05 Jun 2007, 10:36
The set S of numbers has the following properties: 1) If x 5 05 Aug 2006, 01:05
The set S of numbers has the following properties 1 16 Oct 2005, 10:57
3 A set of numbers has the property that for any number t in 16 12 Apr 2005, 08:30
Display posts from previous: Sort by