|
Author |
Message |
|
TAGS:
|
|
|
Intern
Joined: 26 Jun 2012
Posts: 10
Followers: 0
Kudos [?]:
1
[0], given: 9
|
For a certain set of numbers, if x is in the set, then x - 3 [#permalink]
 30 Jul 2012, 07:45
Question Stats:
63% (01:39) correct
36% (00:46) wrong based on 77 sessions
For a certain set of numbers, if x is in the set, then x - 3 is also in the set. If the number 1 is in the set , which of the following must also be in the set ? a) 4 b) -1 c) -5 A. a only, B. b only, C. c only, D. a and b only E. b and c only I need to know why can't x-3 = 1 be considered? if yes then x = 4 (which is not the answer  )
Last edited by Bunuel on 30 Jul 2012, 07:54, edited 2 times in total.
Renamed the topic.
|
|
|
|
|
|
|
GMAT Club team member
Joined: 02 Sep 2009
Posts: 12120
Followers: 1879
Kudos [?]:
10137
[3] , given: 968
|
Re: For a certain set of numbers, if x is in the set, then x - 3 [#permalink]
30 Jul 2012, 08:02
3
This post received
KUDOS
jayoptimist wrote: For a certain set of numbers, if x is in the set, then x - 3 is also in the set. If the number 1 is in the set , which of the following must also be in the set ? a) 4 b) -1 c) -5 A. a only, B. b only, C. c only, D. a and b only E. b and c only I need to know why can't x-3 = 1 be considered? if yes then x = 4 (which is not the answer ) Notice that the question asks which of the following MUST be in the set, not COULD be in the set. Since 1 is in the set, then so must be 1-3=-2. Similarly, since -2 is in the set, then so must be -2-3=-5. Could 4 and -1 be in the set? Certainly, but we don't know that for sure. Answer: C. Regarding your question: we don't know which is the source integer in the set, if it's 1, then 4 won't be in the set but if the source integer is say 7, then 4 will be in the set. So, 4 may or may not be in the set. Similar questions to practice: a-set-of-numbers-has-the-property-that-for-any-number-t-in-t-98829.htmlk-is-a-set-of-integers-such-that-if-the-integer-r-is-in-k-103005.htmlP.S. Please read and follow: rules-for-posting-please-read-this-before-posting-133935.html (rule #3).
_________________
NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!
PLEASE READ AND FOLLOW: 11 Rules for Posting!!!
RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders
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. NEW!!! ,11 Mixed Questions NEW!!!, 12 Fresh Meat NEW!!!
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. NEW!!!, 11 New DS set. NEW!!!
What are GMAT Club Tests?
25 extra-hard Quant Tests
Find out what's new at GMAT Club - latest features and updates
|
|
|
|
|
|
Intern
Joined: 17 Nov 2012
Posts: 21
Followers: 1
Kudos [?]:
1
[0], given: 6
|
For a certain set of numbers, if x is in the set, x-3 is als [#permalink]
30 Dec 2012, 17:22
For a certain set of numbers, if x is in the set, x-3 is also in the set. If the number 1 is in the set, which of the following must also be in the set
I) 4
II) -1
III) -5
the answer is III only, means -5.
They are reasoning that, 1 in the set, so -2 also in the set, so -5 also in the set, so -8 also in the set.
I wonder why 4 can't be in the set??? let consider 1 is x-3, not x, hence x = 4.
What is the trap of GMAT here?
(I always have problem with the trap of gmat)
|
|
|
|
|
|
Director
Joined: 02 Jul 2012
Posts: 790
Location: India
Concentration: Strategy
GMAT 1: 740 Q49 V42
GPA: 3.8
WE: Engineering (Energy and Utilities)
Followers: 19
Kudos [?]:
277
[1] , given: 45
|
Re: For a certain set of numbers, if x is in the set, x-3 is als [#permalink]
30 Dec 2012, 21:40
1
This post received
KUDOS
akhandamandala wrote: For a certain set of numbers, if x is in the set, x-3 is also in the set. If the number 1 is in the set, which of the following must also be in the set
I) 4
II) -1
III) -5
the answer is III only, means -5.
They are reasoning that, 1 in the set, so -2 also in the set, so -5 also in the set, so -8 also in the set.
I wonder why 4 can't be in the set??? let consider 1 is x-3, not x, hence x = 4.
What is the trap of GMAT here?
(I always have problem with the trap of gmat) We can look at this as a cause and effect problem. "x" is the cause and "x-3" is the effect. i.e. We are given that is "x" is in the set "x-3" is also in the set. The reverse need not necessarily be true. We cannot take the effect to be the cause.
_________________
Kudos Please... If my post helped.
Thanks To The Almighty - My GMAT Debrief
My Own CR Question 1|My Own CR Question 2|My Own DS Question 1|My Own DS Question 2|
My Own PS Question 1
|
|
|
|
|
|
GMAT Club team member
Joined: 02 Sep 2009
Posts: 12120
Followers: 1879
Kudos [?]:
10137
[0], given: 968
|
Re: For a certain set of numbers, if x is in the set, x-3 is als [#permalink]
31 Dec 2012, 03:06
akhandamandala wrote: For a certain set of numbers, if x is in the set, x-3 is also in the set. If the number 1 is in the set, which of the following must also be in the set
I) 4
II) -1
III) -5
the answer is III only, means -5.
They are reasoning that, 1 in the set, so -2 also in the set, so -5 also in the set, so -8 also in the set.
I wonder why 4 can't be in the set??? let consider 1 is x-3, not x, hence x = 4.
What is the trap of GMAT here?
(I always have problem with the trap of gmat) Merging similar topics. Please refer to the solutions above.
_________________
NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!
PLEASE READ AND FOLLOW: 11 Rules for Posting!!!
RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders
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. NEW!!! ,11 Mixed Questions NEW!!!, 12 Fresh Meat NEW!!!
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. NEW!!!, 11 New DS set. NEW!!!
What are GMAT Club Tests?
25 extra-hard Quant Tests
Find out what's new at GMAT Club - latest features and updates
|
|
|
|
|
|
Intern
Joined: 17 Nov 2012
Posts: 21
Followers: 1
Kudos [?]:
1
[0], given: 6
|
Re: For a certain set of numbers, if x is in the set, then x - 3 [#permalink]
31 Dec 2012, 12:11
great!!!, thanks guys 
|
|
|
|
|
|
Intern
Joined: 21 Mar 2009
Posts: 21
Followers: 0
Kudos [?]:
7
[0], given: 0
|
Re: For a certain set of numbers, if x is in the set, then x - 3 [#permalink]
31 Dec 2012, 12:21
jayoptimist wrote: For a certain set of numbers, if x is in the set, then x - 3 is also in the set. If the number 1 is in the set , which of the following must also be in the set ? a) 4 b) -1 c) -5 A. a only, B. b only, C. c only, D. a and b only E. b and c only I need to know why can't x-3 = 1 be considered? if yes then x = 4 (which is not the answer ) I call them Verbal diaorea of GMAT. You have to follow these verbal vomits carefully. When they say x-3 is there only x-3 is guaranteed to be there nothing else. And so here you can not travel to the side of the stream.
|
|
|
|
|
|
Intern
Joined: 17 Nov 2012
Posts: 21
Followers: 1
Kudos [?]:
1
[0], given: 6
|
Re: For a certain set of numbers, if x is in the set, then x - 3 [#permalink]
31 Dec 2012, 17:56
maibhihun wrote: jayoptimist wrote: For a certain set of numbers, if x is in the set, then x - 3 is also in the set. If the number 1 is in the set , which of the following must also be in the set ? a) 4 b) -1 c) -5 A. a only, B. b only, C. c only, D. a and b only E. b and c only I need to know why can't x-3 = 1 be considered? if yes then x = 4 (which is not the answer ) I call them Verbal diaorea of GMAT. You have to follow these verbal vomits carefully. When they say x-3 is there only x-3 is guaranteed to be there nothing else. And so here you can not travel to the side of the stream. that's true, I have no problem with math, but I have quite problem with those kinds of "Verbal diaorea of GMAT". Hope exercises will help much. Thanks
|
|
|
|
|
|
|
Re: For a certain set of numbers, if x is in the set, then x - 3
[#permalink]
31 Dec 2012, 17:56
|
|
|
|
|
|
|
|
|
Similar topics |
Author |
Replies |
Last post |
|
Similar
Topics:
|
 |
|
|
If X is a set of numbers {1,3,5} and Y is a set of number
|
MA |
9 |
21 Jan 2005, 23:26 |
|
|
|
|
If X is in a set, x-3 is in the set also. If 1 is in the
|
DLMD |
2 |
03 Feb 2005, 14:23 |
|
|
|
|
Set S contains four elements 3, 4, 5 and x. If x is a number
|
kevincan |
5 |
20 Jul 2006, 03:54 |
|
|
|
 |
For a certain set of 3 numbers, is the average
|
tirupatibalaji |
1 |
15 Jan 2011, 14:33 |
|
|
1
|
|
For a certain set of 3 numbers, is the average
|
enigma123 |
1 |
27 Feb 2012, 16:50 |
|
|
|
|
|
|
close
