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

 It is currently 22 May 2013, 03:37

# NUmber properties

Author Message
TAGS:
Manager
Joined: 10 Jan 2010
Posts: 117
GPA: 4
WE: Programming (Computer Software)
Followers: 0

Kudos [?]: 29 [1] , given: 33

NUmber properties [#permalink]  24 Sep 2011, 15:39
1
KUDOS
00:00

Question Stats:

45% (02:26) correct 55% (01:12) wrong based on 1 sessions
If y not= 3 and 2x/y is a prime integer greater than 2, which of the following must
be true?
I. x = y
II. y = 1
III. x and y are prime integers.
(A) None
(B) I only
(C) II only
(D) III only
(E) I and II
_________________

-If you like my post, consider giving KUDOS

Director
Joined: 01 Feb 2011
Posts: 792
Followers: 11

Kudos [?]: 62 [0], given: 42

Re: NUmber properties [#permalink]  24 Sep 2011, 17:44
given 2x/y is prime and greater than 2.

=> 2x/y could be any of the following
3,5,7....
=> 2x/y is odd and prime (as 2 is the only even prime number and its not in this set)

1. x = y , can't be true

if x=y , 2x/y = 2 which is not odd and prime.

2. y=1. can't be true.

if y=1,2x/y = 2x = even which is not odd & prime.

3. x and y are prime integers, need not be true.

lets say 2x/y = 3 and say y=2 prime
=>x = 6/2 = 3 prime
satisfies the given condition here.

but when 2x/y = 3 and y=5 prime

=> x = 15/2 not prime

Math Forum Moderator
Joined: 20 Dec 2010
Posts: 2100
Followers: 108

Kudos [?]: 655 [0], given: 376

Re: NUmber properties [#permalink]  24 Sep 2011, 18:09
maheshsrini wrote:
If y not= 3 and 2x/y is a prime integer greater than 2, which of the following must
be true?
I. x = y
II. y = 1
III. x and y are prime integers.
(A) None
(B) I only
(C) II only
(D) III only
(E) I and II

I. x = y. Not true AS 2x/y will become 2

II. y = 1
III. x and y are prime integers.
x=26; y=4; Falsifies both II & III, without violating any of the conditions.

Ans: "A"
_________________
Manager
Joined: 10 Jan 2010
Posts: 117
GPA: 4
WE: Programming (Computer Software)
Followers: 0

Kudos [?]: 29 [0], given: 33

Re: NUmber properties [#permalink]  24 Sep 2011, 20:19
I found this problem in the web and did not find the OA. My approach was the same and wanted to confirm the answer.
_________________

-If you like my post, consider giving KUDOS

Senior Manager
Joined: 11 May 2011
Posts: 383
Location: US
Followers: 1

Kudos [?]: 46 [0], given: 46

Re: NUmber properties [#permalink]  24 Sep 2011, 21:42
"A" from my side as well. No option satisfy the criteria.

Cheers!
_________________

-----------------------------------------------------------------------------------------
What you do TODAY is important because you're exchanging a day of your life for it!
-----------------------------------------------------------------------------------------

Re: NUmber properties   [#permalink] 24 Sep 2011, 21:42
Similar topics Replies Last post
Similar
Topics:
Number Properties 3 19 Oct 2005, 18:14
Number properties 6 03 Apr 2006, 20:00
Number Properties 3 10 Sep 2006, 12:43
Number Property 4 19 Sep 2006, 16:04
Number properties?!?!?! 0 09 Nov 2006, 07:17
Display posts from previous: Sort by