Author 
Message 
TAGS:

Hide Tags

Manager
Status: Never ever give up on yourself.Period.
Joined: 23 Aug 2012
Posts: 152
Location: India
Concentration: Finance, Human Resources
GMAT 1: 570 Q47 V21 GMAT 2: 690 Q50 V33
GPA: 3.5
WE: Information Technology (Investment Banking)

Is 30 a factor of n? [#permalink]
Show Tags
04 Jan 2013, 07:33
3
This post was BOOKMARKED
Question Stats:
32% (01:56) correct
68% (01:05) wrong based on 94 sessions
HideShow timer Statistics
Is 30 a factor of n? (1) 30 is a factor of the square of n (2) 30 is a factor of 2n I doubt on OA...plz clarify
Official Answer and Stats are available only to registered users. Register/ Login.
_________________
Don't give up on yourself ever. Period. Beat it, no one wants to be defeated (My journey from 570 to 690) : http://gmatclub.com/forum/beatitnoonewantstobedefeatedjourney570to149968.html



Moderator
Joined: 02 Jul 2012
Posts: 1223
Location: India
Concentration: Strategy
GPA: 3.8
WE: Engineering (Energy and Utilities)

Re: Is 30 a factor of n? [#permalink]
Show Tags
04 Jan 2013, 07:43
daviesj wrote: is 30 a factor of n? (1) 30 is a factor of the square of n (2) 30 is a factor of 2n
I doubt on OA...plz clarify 1) If n is \(\sqrt{30}\), Answer is no. If n is 30, answer is yes. Insufficient. 2)If n = 15, answer is no. If n = 30, answer is yes. Insufficient. 1 & 2 together. 2n has to be an even number to be divisible by 30. Hence, n has to be an integer. \(n^2\) is divisible by 30. So \(n^2\) should have at least one 2, one 3 and one 5. Since \(n^2\) is the square of an integer, this further implies that n^2 has to have at least two 2s, two 3s and two 5s. Hence n has at least one 2, one 3 and one 5. Hence divisible. Answer is C
_________________
Did you find this post helpful?... Please let me know through the Kudos button.
Thanks To The Almighty  My GMAT Debrief
GMAT Reading Comprehension: 7 Most Common Passage Types



Math Expert
Joined: 02 Sep 2009
Posts: 39725

Re: Is 30 a factor of n? [#permalink]
Show Tags
04 Jan 2013, 07:45
4
This post received KUDOS
Expert's post
2
This post was BOOKMARKED
daviesj wrote: Is 30 a factor of n?
(1) 30 is a factor of the square of n (2) 30 is a factor of 2n
I doubt on OA...plz clarify Every GMAT divisibility question will tell you in advance that any unknowns represent positive integers, which means that ALL GMAT divisibility questions are limited to positive integers only.If n is not an integer, then the question does not make sense (at least for GMAT) . The question should read: If n is an integer, is 30 a factor of n?(1) 30 is a factor of n^2. If 30=2*3*5 is not a factor of n (if 2, 3 and 5 are not factors of n), then how this factors could appear in n^2? Exponentiation doesn't "produce" primes. Sufficient. (2) 30 is a factor of 2n. Clearly insufficient: if n=15 then the answer is NO but if n=30 then the answer is YES. Not sufficient. Answer: A.
_________________
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



Moderator
Joined: 02 Jul 2012
Posts: 1223
Location: India
Concentration: Strategy
GPA: 3.8
WE: Engineering (Energy and Utilities)

Re: Is 30 a factor of n? [#permalink]
Show Tags
04 Jan 2013, 07:51
Bunuel wrote: daviesj wrote: Is 30 a factor of n?
(1) 30 is a factor of the square of n (2) 30 is a factor of 2n
I doubt on OA...plz clarify Every GMAT divisibility question will tell you in advance that any unknowns represent positive integers, which means that ALL GMAT divisibility questions are limited to positive integers only.If n is not an integer, then the question does not make sense (at least for GMAT) . The question should read: If n is an integer, is 30 a factor of n?(1) 30 is a factor of n^2. If 30=2*3*5 is not a factor of n (if 2, 3 and 5 are not factors of n), then how this factors could appear in n^2? Exponentiation doesn't "produce" primes. Sufficient. (2) 30 is a factor of 2n. Clearly insufficient: if n=15 then the answer is NO but if n=30 then the answer is YES. Not sufficient. Answer: A. Hi Bunuel, Just curious.. Why would the question not make sense if "n" were not an integer?
_________________
Did you find this post helpful?... Please let me know through the Kudos button.
Thanks To The Almighty  My GMAT Debrief
GMAT Reading Comprehension: 7 Most Common Passage Types



Math Expert
Joined: 02 Sep 2009
Posts: 39725

Re: Is 30 a factor of n? [#permalink]
Show Tags
04 Jan 2013, 08:01
MacFauz wrote: Bunuel wrote: daviesj wrote: Is 30 a factor of n?
(1) 30 is a factor of the square of n (2) 30 is a factor of 2n
I doubt on OA...plz clarify Every GMAT divisibility question will tell you in advance that any unknowns represent positive integers, which means that ALL GMAT divisibility questions are limited to positive integers only.If n is not an integer, then the question does not make sense (at least for GMAT) . The question should read: If n is an integer, is 30 a factor of n?(1) 30 is a factor of n^2. If 30=2*3*5 is not a factor of n (if 2, 3 and 5 are not factors of n), then how this factors could appear in n^2? Exponentiation doesn't "produce" primes. Sufficient. (2) 30 is a factor of 2n. Clearly insufficient: if n=15 then the answer is NO but if n=30 then the answer is YES. Not sufficient. Answer: A. Hi Bunuel, Just curious.. Why would the question not make sense if "n" were not an integer? It does not make sense for GMAT since only integers can have factors.
_________________
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



Manager
Status: Never ever give up on yourself.Period.
Joined: 23 Aug 2012
Posts: 152
Location: India
Concentration: Finance, Human Resources
GMAT 1: 570 Q47 V21 GMAT 2: 690 Q50 V33
GPA: 3.5
WE: Information Technology (Investment Banking)

Re: Is 30 a factor of n? [#permalink]
Show Tags
04 Jan 2013, 08:59
Thanks Bunuel, I used the same logic as you did. that's why I didn't get C as answer...Thanks for the clarification..+1 Kudos
_________________
Don't give up on yourself ever. Period. Beat it, no one wants to be defeated (My journey from 570 to 690) : http://gmatclub.com/forum/beatitnoonewantstobedefeatedjourney570to149968.html



Intern
Joined: 16 Apr 2009
Posts: 16

Re: Is 30 a factor of n? [#permalink]
Show Tags
04 Jan 2013, 23:12
Bunuel wrote: daviesj wrote: Is 30 a factor of n?
(1) 30 is a factor of the square of n (2) 30 is a factor of 2n
I doubt on OA...plz clarify Every GMAT divisibility question will tell you in advance that any unknowns represent positive integers, which means that ALL GMAT divisibility questions are limited to positive integers only.If n is not an integer, then the question does not make sense (at least for GMAT) . The question should read: If n is an integer, is 30 a factor of n?(1) 30 is a factor of n^2. If 30=2*3*5 is not a factor of n (if 2, 3 and 5 are not factors of n), then how this factors could appear in n^2? Exponentiation doesn't "produce" primes. Sufficient. (2) 30 is a factor of 2n. Clearly insufficient: if n=15 then the answer is NO but if n=30 then the answer is YES. Not sufficient. Answer: A. Bunnel Is it not possible that for Statement 1: If the number is 900 and 30 is a factor of 900, then it is possible that 30 (which is ) is a factor of the square root of 900. In the contrary, 60 is also a factor of 900 but is not a factor of the square root of 900. Please shed some light.. Thanks



Math Expert
Joined: 02 Sep 2009
Posts: 39725

Re: Is 30 a factor of n? [#permalink]
Show Tags
05 Jan 2013, 03:35
Drik wrote: Bunuel wrote: daviesj wrote: Is 30 a factor of n?
(1) 30 is a factor of the square of n (2) 30 is a factor of 2n
I doubt on OA...plz clarify Every GMAT divisibility question will tell you in advance that any unknowns represent positive integers, which means that ALL GMAT divisibility questions are limited to positive integers only.If n is not an integer, then the question does not make sense (at least for GMAT) . The question should read: If n is an integer, is 30 a factor of n?(1) 30 is a factor of n^2. If 30=2*3*5 is not a factor of n (if 2, 3 and 5 are not factors of n), then how this factors could appear in n^2? Exponentiation doesn't "produce" primes. Sufficient. (2) 30 is a factor of 2n. Clearly insufficient: if n=15 then the answer is NO but if n=30 then the answer is YES. Not sufficient. Answer: A. Bunnel Is it not possible that for Statement 1: If the number is 900 and 30 is a factor of 900, then it is possible that 30 (which is ) is a factor of the square root of 900. In the contrary, 60 is also a factor of 900 but is not a factor of the square root of 900. Please shed some light.. Thanks If prime number p is a factor of n^2 (where n is a positive integer), then p must be a factor of n. So, the fact that 2, 3, and 5 are factors of n^2 means that 2, 3 and 5 must also be factors of n. But if p^2 is a factor of n^2 (where n is a positive integer), then p^2 may or may not be a factor of n. For example, if 60=2^2*3*5 is a factor of n^2, then all primes of 60 must also be factors of n, but 2^2 may or may not be a factor of n, so 60 may or may not be a factor of n. Hope it's clear.
_________________
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



GMAT Club Legend
Joined: 09 Sep 2013
Posts: 16014

Re: Is 30 a factor of n? [#permalink]
Show Tags
11 Nov 2014, 03:55
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



Manager
Joined: 14 Jul 2014
Posts: 191
Location: United States
GMAT 1: 600 Q48 V27 GMAT 2: 720 Q50 V37
GPA: 3.2

Re: Is 30 a factor of n? [#permalink]
Show Tags
23 Mar 2016, 11:02
what is the correct answer? Bunuel says A but the answer is C?



Math Expert
Joined: 02 Sep 2009
Posts: 39725

Re: Is 30 a factor of n? [#permalink]
Show Tags
23 Mar 2016, 11:05



Intern
Joined: 16 Apr 2015
Posts: 34

Re: Is 30 a factor of n? [#permalink]
Show Tags
23 Mar 2016, 11:39
Bunuel wrote: daviesj wrote: Is 30 a factor of n?
(1) 30 is a factor of the square of n (2) 30 is a factor of 2n
I doubt on OA...plz clarify Every GMAT divisibility question will tell you in advance that any unknowns represent positive integers, which means that ALL GMAT divisibility questions are limited to positive integers only.If n is not an integer, then the question does not make sense (at least for GMAT) . The question should read: If n is an integer, is 30 a factor of n?(1) 30 is a factor of n^2. If 30=2*3*5 is not a factor of n (if 2, 3 and 5 are not factors of n), then how this factors could appear in n^2? Exponentiation doesn't "produce" primes. Sufficient. (2) 30 is a factor of 2n. Clearly insufficient: if n=15 then the answer is NO but if n=30 then the answer is YES. Not sufficient. Answer: A. Hello Bunuel, Is there a reference for your statement Every GMAT divisibility question will tell you in advance that any unknowns represent positive integers, which means that ALL GMAT divisibility questions are limited to positive integers only.somewhere in GMAT official guide. I am little confused here, because almost in every DS question we are told to not assume a number as +ve or as integer unless otherwise advised. In my opinion, given in this question we must not assume that "n" is positive integer.



Math Expert
Joined: 02 Sep 2009
Posts: 39725

Re: Is 30 a factor of n? [#permalink]
Show Tags
23 Mar 2016, 11:43
sameerspice wrote: Bunuel wrote: daviesj wrote: Is 30 a factor of n?
(1) 30 is a factor of the square of n (2) 30 is a factor of 2n
I doubt on OA...plz clarify Every GMAT divisibility question will tell you in advance that any unknowns represent positive integers, which means that ALL GMAT divisibility questions are limited to positive integers only.If n is not an integer, then the question does not make sense (at least for GMAT) . The question should read: If n is an integer, is 30 a factor of n?(1) 30 is a factor of n^2. If 30=2*3*5 is not a factor of n (if 2, 3 and 5 are not factors of n), then how this factors could appear in n^2? Exponentiation doesn't "produce" primes. Sufficient. (2) 30 is a factor of 2n. Clearly insufficient: if n=15 then the answer is NO but if n=30 then the answer is YES. Not sufficient. Answer: A. Hello Bunuel, Is there a reference for your statement Every GMAT divisibility question will tell you in advance that any unknowns represent positive integers, which means that ALL GMAT divisibility questions are limited to positive integers only.somewhere in GMAT official guide. I am little confused here, because almost in every DS question we are told to not assume a number as +ve or as integer unless otherwise advised. In my opinion, given in this question we must not assume that "n" is positive integer. I'm not saying that one should assume this. I'm saying that in its current form the question is NOT GMAT like because every GMAT divisibility question will tell you in advance that any unknowns represent positive integers. So, if it were proper GMAT question we would be given that n is an integer.
_________________
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



Intern
Joined: 16 Apr 2015
Posts: 34

Is 30 a factor of n? [#permalink]
Show Tags
23 Mar 2016, 12:06
Quote: I'm not saying that one should assume this. I'm saying that in its current form the question is NOT GMAT like because every GMAT divisibility question will tell you in advance that any unknowns represent positive integers. So, if it were proper GMAT question we would be given that n is an integer. Thank Bunuel, this makes lot of sense and explain the question OA to me now.



Manager
Joined: 14 Jul 2014
Posts: 191
Location: United States
GMAT 1: 600 Q48 V27 GMAT 2: 720 Q50 V37
GPA: 3.2

Re: Is 30 a factor of n? [#permalink]
Show Tags
23 Mar 2016, 12:59
Bunuel, if we see a divisibility question and integer details are not mentioned, should we assume that it is an integer because GMAT does mention usually? (probably asking the same question the other user asked  just wanted to confirm)



Math Expert
Joined: 02 Sep 2009
Posts: 39725

Re: Is 30 a factor of n? [#permalink]
Show Tags
23 Mar 2016, 13:12




Re: Is 30 a factor of n?
[#permalink]
23 Mar 2016, 13:12








Similar topics 
Author 
Replies 
Last post 
Similar Topics:


2


For positive integer n, is 12 a factor of n?

MathRevolution 
2 
14 May 2017, 18:31 

1


If n and m are positive integers, is m a factor of n?

Mo2men 
2 
17 Jan 2017, 01:14 

2


If n is the integer, whether 30 is a factor of n?

LM 
3 
14 Nov 2014, 00:47 

9


If N is a positive integer, is 9 a factor of N?

Jinglander 
12 
20 Aug 2016, 11:49 

9


If n and t are positive integers, is n a factor of t?

arvs212 
8 
26 Aug 2016, 05:50 



