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

It is currently 24 Oct 2014, 01:56

Close

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
Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If N is a positive integer, not including N, how many

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Senior Manager
Senior Manager
User avatar
Joined: 04 Sep 2008
Posts: 261
Location: Kolkata
Schools: La Martiniere for Boys
Followers: 2

Kudos [?]: 26 [0], given: 9

If N is a positive integer, not including N, how many [#permalink] New post 27 Oct 2008, 01:19
1
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

21% (01:24) correct 79% (00:59) wrong based on 23 sessions
If N is a positive integer, not including N, how many factors does N have?

(1) Not including N^2, N^2 has 4 factors.

(2) Not including 2N, 2N has 3 factors.
[Reveal] Spoiler: OA

_________________

Thanks
rampuria

SVP
SVP
avatar
Joined: 17 Jun 2008
Posts: 1578
Followers: 12

Kudos [?]: 186 [0], given: 0

Re: Number Property DS [#permalink] New post 27 Oct 2008, 02:28
Is it D?

stmt1: Excluding N^2, it has 4 factors. Two of these will be 1 and N. Two other factors are possible only when N is the square of a prime number. Suppose, N = p^2, then two other factors of N^2 will be p and N*p. Hence, sufficient.

stmt2: Excluding 2N, N has 3 factors. These will be 1, 2, N. That means, N itself is a prime number. Hence, sufficient.
SVP
SVP
avatar
Joined: 17 Jun 2008
Posts: 1578
Followers: 12

Kudos [?]: 186 [0], given: 0

Re: DS - number theory [#permalink] New post 03 Nov 2008, 01:41
B.

From stmt1: N^2 has 1, N and two more factors (excluding N^2). Both these factors could also be of N or, only one of them is of N. Hence, insufficient.

From stmt2: 2N has 1, 2 and N as factors (excluding 2N). Hence, N must be a prime number. Hence, sufficient.
Manager
Manager
User avatar
Joined: 24 Sep 2008
Posts: 194
Schools: MIT / INSEAD / IIM - ABC
Followers: 1

Kudos [?]: 24 [0], given: 7

Re: DS - number theory [#permalink] New post 03 Nov 2008, 02:53
scthakur wrote:
B.

From stmt1: N^2 has 1, N and two more factors (excluding N^2). Both these factors could also be of N or, only one of them is of N. Hence, insufficient.

From stmt2: 2N has 1, 2 and N as factors (excluding 2N). Hence, N must be a prime number. Hence, sufficient.


My friend in my opinion stmnt 1 is SUFF.....and 2 is also SUFF...so i picked D but OA is A
Current Student
avatar
Joined: 28 Dec 2004
Posts: 3403
Location: New York City
Schools: Wharton'11 HBS'12
Followers: 13

Kudos [?]: 164 [0], given: 2

Re: DS - number theory [#permalink] New post 03 Nov 2008, 07:18
GODSPEED wrote:
If N is a positive integer, not including N, how many factors does N have?

A - Not including N^2, N^2 has 4 factors
B - Not including 2N, 2N has 3 factors



so lets assume N=a^x b^y where a and b are prime factors so no of factors is (x+1)(y+1)

1)
anyways N^2 has 4 factors not inlcuding N^2 means N has only one prime factor

lets see, N^2=16, then factors are 1, 2, 4, 8 And 16 <--N^2

if N^2=81, then factors are 1, 3, 9, 27...

N has 3 factors given..

2) 2N has factors i.e 2N i.e. 2^1 so N has to be 3 or 5..SUff

I will go with D.
SVP
SVP
avatar
Joined: 17 Jun 2008
Posts: 1578
Followers: 12

Kudos [?]: 186 [0], given: 0

Re: DS - number theory [#permalink] New post 03 Nov 2008, 09:55
GODSPEED wrote:
scthakur wrote:
B.

From stmt1: N^2 has 1, N and two more factors (excluding N^2). Both these factors could also be of N or, only one of them is of N. Hence, insufficient.

From stmt2: 2N has 1, 2 and N as factors (excluding 2N). Hence, N must be a prime number. Hence, sufficient.


My friend in my opinion stmnt 1 is SUFF.....and 2 is also SUFF...so i picked D but OA is A


I need a break :oops: making too many silly mistakes today.

Yes, OA should be A.

In stmt2: if N = 4, 2N =8 and it has 1, 2, 4 as factors (excluding 8). But, N has 1,2,4 as factors.
However, if N = 3, 2N = 6 and it has 1, 2,3 as factors (excluding 6). However, N has only 1 and 3 as factors. Hence, insufficient.
Current Student
avatar
Joined: 28 Dec 2004
Posts: 3403
Location: New York City
Schools: Wharton'11 HBS'12
Followers: 13

Kudos [?]: 164 [0], given: 2

Re: DS - number theory [#permalink] New post 03 Nov 2008, 10:05
stmnt 2..if 2N=6 then say N=3, factors of 6 are 1, 2, 3 6<--not included , N=3 factors are 1 and 3..

if 2N=8 then factors are 1,2,4 8<--not included N=2 factors are 1 and 2

all stmnt 2 is say N is a prime number

I think D.

scthakur wrote:
GODSPEED wrote:
scthakur wrote:
B.

From stmt1: N^2 has 1, N and two more factors (excluding N^2). Both these factors could also be of N or, only one of them is of N. Hence, insufficient.

From stmt2: 2N has 1, 2 and N as factors (excluding 2N). Hence, N must be a prime number. Hence, sufficient.


My friend in my opinion stmnt 1 is SUFF.....and 2 is also SUFF...so i picked D but OA is A


I need a break :oops: making too many silly mistakes today.

Yes, OA should be A.

In stmt2: if N = 4, 2N =8 and it has 1, 2, 4 as factors (excluding 8). But, N has 1,2,4 as factors.
However, if N = 3, 2N = 6 and it has 1, 2,3 as factors (excluding 6). However, N has only 1 and 3 as factors. Hence, insufficient.
SVP
SVP
avatar
Joined: 17 Jun 2008
Posts: 1578
Followers: 12

Kudos [?]: 186 [0], given: 0

Re: DS - number theory [#permalink] New post 03 Nov 2008, 10:14
fresinha12 wrote:
stmnt 2..if 2N=6 then say N=3, factors of 6 are 1, 2, 3 6<--not included , N=3 factors are 1 and 3..

if 2N=8 then factors are 1,2,4 8<--not included N=2 factors are 1 and 2
all stmnt 2 is say N is a prime number

I think D.


Here, N will be 4 and its factors will be 1,2,4.
Current Student
avatar
Joined: 28 Dec 2004
Posts: 3403
Location: New York City
Schools: Wharton'11 HBS'12
Followers: 13

Kudos [?]: 164 [0], given: 2

Re: DS - number theory [#permalink] New post 03 Nov 2008, 10:25
looks like you are not the only one having a bad day...

agree with A as ans..
Intern
Intern
avatar
Joined: 01 Aug 2006
Posts: 35
Followers: 0

Kudos [?]: 13 [0], given: 0

Re: If N is a positive integer, not including N, how many [#permalink] New post 07 Feb 2014, 17:17
1
This post was
BOOKMARKED
If N is a positive integer, not including N, how many factors does N have?
(1) Not including N^2, N^2 has 4 factors -> N^2 (a perfect square) has a total of 5 factors => N has 3 factors in total (N is a perfect square of prime number).
example: N = 4; N^2 = 16 (5 factors); N has 2 factors excluding N.
example: N = 9; N^2 = 81 (5 factors); N has 2 factors excluding N.
(2) Not including 2N, 2N has 3 factors -> 2N has a total of 4 factors
For 2N to have a total of 4 factors, N can be 2^2 or (any other prime)^1
example: N = 4; 2N = 8 (4 factors);N has 2 factors excluding N.
example: N = 3; 2N = 6 (4 factors); N has 1 factor excluding N.
NOT SUFFICIENT.
A.
Re: If N is a positive integer, not including N, how many   [#permalink] 07 Feb 2014, 17:17
    Similar topics Author Replies Last post
Similar
Topics:
If n is an integer, then n is divisible by how many positive vinayrsm 6 02 Jul 2011, 00:10
2 Experts publish their posts in the topic If n is an integer, then n divisible by how many positive Baten80 7 19 Feb 2011, 09:29
If N is a positive integer, not including N, how many GODSPEED 0 03 Nov 2008, 10:25
Experts publish their posts in the topic If n is an integer, then n is divisible by how many positive zetaexmachina 3 11 Jun 2008, 22:47
How many positive integers n are there such that n^3 is a kevincan 6 18 Aug 2006, 04:46
Display posts from previous: Sort by

If N is a positive integer, not including N, how many

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.