GRE Prep 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
Track
Your Progress
Practice
Pays
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
[#permalink]
22 Oct 2017, 06:05
22 Oct 2017, 06:05
00:00
Question Stats:
36% (00:40) correct
63% (00:55) wrong based on 11 sessions
Hide Show timer Statistics
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.
(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.
Manager
Joined: 01 Apr 2017
Posts: 61
Given Kudos: 0
WE:Analyst (Computer Software)
Re: c and d are prime numbers. If c - d is an odd prime, then wh
[#permalink]
24 Oct 2017, 13:23
24 Oct 2017, 13:23
1
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.
So,only option which must be true is option (D) i.e. "d" is even.
Re: c and d are prime numbers. If c - d is an odd prime, then wh
[#permalink]
25 Oct 2017, 08:10
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.
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
