Aug 19 08:00 AM PDT  09:00 AM PDT Join a 4day FREE online boot camp to kick off your GMAT preparation and get you into your dream bschool in R1.**Limited for the first 99 registrants. Register today! Aug 20 08:00 PM PDT  09:00 PM PDT EMPOWERgmat is giving away the complete Official GMAT Exam Pack collection worth $100 with the 3 Month Pack ($299) Aug 20 09:00 PM PDT  10:00 PM PDT Take 20% off the plan of your choice, now through midnight on Tuesday, 8/20 Aug 22 09:00 PM PDT  10:00 PM PDT What you'll gain: Strategies and techniques for approaching featured GMAT topics, and much more. Thursday, August 22nd at 9 PM EDT Aug 24 07:00 AM PDT  09:00 AM PDT Learn reading strategies that can help even nonvoracious reader to master GMAT RC Aug 25 09:00 AM PDT  12:00 PM PDT Join a FREE 1day verbal workshop and learn how to ace the Verbal section with the best tips and strategies. Limited for the first 99 registrants. Register today! Aug 25 08:00 PM PDT  11:00 PM PDT Exclusive offer! Get 400+ Practice Questions, 25 Video lessons and 6+ Webinars for FREE.
Author 
Message 
TAGS:

Hide Tags

Intern
Joined: 26 Jun 2012
Posts: 8

For a certain set of numbers, if x is in the set, then x  3
[#permalink]
Show Tags
Updated on: 04 Nov 2018, 09:51
Question Stats:
69% (01:00) correct 31% (01:23) wrong based on 356 sessions
HideShow timer Statistics
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 x3 = 1 be considered? if yes then x = 4 (which is not the answer )
Official Answer and Stats are available only to registered users. Register/ Login.
Originally posted by jayoptimist on 30 Jul 2012, 07:45.
Last edited by gmat1393 on 04 Nov 2018, 09:51, edited 3 times in total.
Reformatting




Math Expert
Joined: 02 Sep 2009
Posts: 57030

Re: For a certain set of numbers, if x is in the set, then x  3
[#permalink]
Show Tags
30 Jul 2012, 08:02
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 x3 = 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 13=2. Similarly, since 2 is in the set, then so must be 23=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: asetofnumbershasthepropertythatforanynumbertint98829.htmlkisasetofintegerssuchthatiftheintegerrisink103005.htmlP.S. Please read and follow: rulesforpostingpleasereadthisbeforeposting133935.html (rule #3).
_________________




Intern
Joined: 17 Nov 2012
Posts: 17

Re: For a certain set of numbers, if x is in the set, then x  3
[#permalink]
Show Tags
30 Dec 2012, 17:22
For a certain set of numbers, if x is in the set, x3 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 x3, not x, hence x = 4. What is the trap of GMAT here?
(I always have problem with the trap of gmat)



VP
Joined: 02 Jul 2012
Posts: 1145
Location: India
Concentration: Strategy
GPA: 3.8
WE: Engineering (Energy and Utilities)

Re: For a certain set of numbers, if x is in the set, then x  3
[#permalink]
Show Tags
30 Dec 2012, 21:40
akhandamandala wrote: For a certain set of numbers, if x is in the set, x3 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 x3, 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 "x3" is the effect. i.e. We are given that is "x" is in the set "x3" is also in the set. The reverse need not necessarily be true. We cannot take the effect to be the cause.
_________________



Intern
Joined: 21 Mar 2009
Posts: 16

Re: For a certain set of numbers, if x is in the set, then x  3
[#permalink]
Show Tags
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 x3 = 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 x3 is there only x3 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: 17

Re: For a certain set of numbers, if x is in the set, then x  3
[#permalink]
Show Tags
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 x3 = 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 x3 is there only x3 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



Intern
Joined: 03 Apr 2014
Posts: 1

Re: For a certain set of numbers, if x is in the set, then x  3
[#permalink]
Show Tags
27 Apr 2014, 09:18
It does not make logical sense to only have 5 and 4 is not the correct answer. Can't we take that 1 is the result of X 3 ? In which case, X = 4. I cant agree with 5 more because it is one more "jump" X = 1 .... 2nd number is ( 2 ) is fine with me. But the question did not say that "X  6" also exists? Because X is still 1, and did not "move on" to become 2. Agree its a bit of a "throw you off if you did not buy our official guide" even if you had maths as your bach degree. Hope this kind of stuff don't pop up for my coming exam, but it cant be helped =)



Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 7367
Location: United States (CA)

Re: For a certain set of numbers, if x is in the set, then x  3
[#permalink]
Show Tags
26 Jul 2017, 16:32
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 'If we let x = 1, then (1  3) = 2 is in the set. If 2 is in the set, then (2  3) = 5 is in the set. We can see that if we keep subtracting 3, we will get terms such as 8, 11, 14, etc. We see that 5 is definitely in the set, but 1 isn’t, since if 1 and 2 are in the set, then any numbers between them can’t be in the set. Note: some people might argue that 4 is also in the set, since if we let x  3 = 1, then x = 4. Of course, the answer choices don’t have ‘a and c only’ as an option. The problem says: “if x is in the set, then x  3 is also in the set.” The problem doesn’t say: “if x  3 is in the set, then x is also in the set.” So, when the problem says “if the number 1 is in the set,” we have to assume that 1 is the value of x, and we have to subtract 3 and keep subtracting 3 to get subsequent terms. We can’t assume that 1 is the value of x  3. Answer: C
_________________
5star rated online GMAT quant self study course See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews If you find one of my posts helpful, please take a moment to click on the "Kudos" button.



NonHuman User
Joined: 09 Sep 2013
Posts: 12018

Re: For a certain set of numbers, if x is in the set, then x  3
[#permalink]
Show Tags
14 Aug 2019, 16:12
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.
_________________




Re: For a certain set of numbers, if x is in the set, then x  3
[#permalink]
14 Aug 2019, 16:12






