It is currently 12 Dec 2018, 12:57
My Tests

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.

c and d are prime numbers. If c - d is an odd prime, then wh

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Senior Manager
Senior Manager
Joined: 20 May 2014
Posts: 282
Followers: 15

Kudos [?]: 49 [0], given: 220

CAT Tests
c and d are prime numbers. If c - d is an odd prime, then wh [#permalink] New post 22 Oct 2017, 06:05
00:00

Question Stats:

20% (00:04) correct 80% (00:50) wrong based on 5 sessions
c and d are prime numbers. If c - d is an odd prime, then which of the following must be true?

(A) c is even

(B) d is odd

(C) c*d is odd

(D) d is even

(E) c*d - c is even

Kudos for correct solution.
[Reveal] Spoiler: OA
1 KUDOS received
Manager
Manager
Joined: 01 Apr 2017
Posts: 61
WE: Analyst (Computer Software)
Followers: 0

Kudos [?]: 61 [1] , given: 27

Re: c and d are prime numbers. If c - d is an odd prime, then wh [#permalink] New post 24 Oct 2017, 13:23
1
This post received
KUDOS
Let c = 7 and d =2. Therefore, c-d=> 7-2 = 5 (odd prime number).

So,only option which must be true is option (D) i.e. "d" is even.
Director
Director
Joined: 03 Sep 2017
Posts: 521
Followers: 1

Kudos [?]: 330 [0], given: 66

Re: c and d are prime numbers. If c - d is an odd prime, then wh [#permalink] New post 25 Oct 2017, 08:10
PankajPatel wrote:
Let c = 7 and d =2. Therefore, c-d=> 7-2 = 5 (odd prime number).

So,only option which must be true is option (D) i.e. "d" is even.



More generally, the only way to get an odd number out of a subtraction is having even-odd or odd-even. Given that 2 is the only prime number and the least, it must be that it is the one which is subtracted, d in our case. Thus, d must be even. Answer E
Re: c and d are prime numbers. If c - d is an odd prime, then wh   [#permalink] 25 Oct 2017, 08:10
Display posts from previous: Sort by

c and d are prime numbers. If c - d is an odd prime, then wh

  Question banks Downloads My Bookmarks Reviews Important topics  


GRE Prep Club Forum Home| About| Terms and Conditions and Privacy Policy| GRE Prep Club Rules| Contact

Powered by phpBB © phpBB Group

Kindly note that the GRE® test is a registered trademark of the Educational Testing Service®, and this site has neither been reviewed nor endorsed by ETS®.