-
knight247
- Legendary Member
- Posts: 504
- Joined: Tue Apr 19, 2011 1:40 pm
- Thanked: 114 times
- Followed by:11 members
If k and n are integers, is n divisible by 7?
(1) n-3=2k
(2) 2k-1 is divisible by 7
This is a problem from the OG. The OA is C. And i got the idea from there. But here is where i have a problem with statement 1
(1) n-3=2k
2k is even. To get an even sum/difference the numbers have to be both odd or both even. Can't have a mix of odd and even. Now, if one odd number i.e. 3 is already there then n has to be odd. Coz if n is even then u can't get an even sum of 2k. So if this statement says n is odd then how could it be divisible by 7. So statement 1 says clearly that n is not divisible by 7(Sufficient). Statement 2 gives no indication by itself of n's divisibility by 7 hence insufficient. Should be A according to me
(1) n-3=2k
(2) 2k-1 is divisible by 7
This is a problem from the OG. The OA is C. And i got the idea from there. But here is where i have a problem with statement 1
(1) n-3=2k
2k is even. To get an even sum/difference the numbers have to be both odd or both even. Can't have a mix of odd and even. Now, if one odd number i.e. 3 is already there then n has to be odd. Coz if n is even then u can't get an even sum of 2k. So if this statement says n is odd then how could it be divisible by 7. So statement 1 says clearly that n is not divisible by 7(Sufficient). Statement 2 gives no indication by itself of n's divisibility by 7 hence insufficient. Should be A according to me
