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#### 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
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Senior Manager Joined: 20 May 2014
Posts: 282
Followers: 18

Kudos [?]: 50 , given: 220

c and d are prime numbers. If c - d is an odd prime, then wh [#permalink] 00:00

Question Stats: 16% (00:04) correct 83% (01:00) wrong based on 6 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 Manager Joined: 01 Apr 2017
Posts: 61
WE: Analyst (Computer Software)
Followers: 0

Kudos [?]: 62  , given: 27

Re: c and d are prime numbers. If c - d is an odd prime, then wh [#permalink]
1
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 Joined: 03 Sep 2017
Posts: 521
Followers: 1

Kudos [?]: 344 , given: 66

Re: c and d are prime numbers. If c - d is an odd prime, then wh [#permalink]
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
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# c and d are prime numbers. If c - d is an odd prime, then wh  Question banks Downloads My Bookmarks Reviews Important topics 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®.