BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

GMATPREP DS.. pls help

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Data Sufficiency |
User avatar
Legendary Member
Posts: 1560
Joined: Tue Nov 17, 2009 2:38 am
Thanked: 137 times
Followed by:5 members

by thephoenix » Sun Feb 07, 2010 1:44 am
s1) n+4=prime no and nis +ve int-----> n is odd
bcoz the only prime no which is even is 2 and rest all are odd
hence n can be 3,7,13,19,27....all odd value only give a prime no.

suff

s2)
n+3 is a prime no.
if n=6(even)
n+3=9 not a prime no

if n=3 (odd)
n+3=6 not a prime no
hence insuff
Top
User avatar
Legendary Member
Posts: 1275
Joined: Thu Sep 21, 2006 11:13 pm
Location: Arabian Sea
Thanked: 125 times
Followed by:2 members

by ajith » Sun Feb 07, 2010 2:52 am
rdchandvadkar wrote:Is the positive integer n an odd integer?

(1) n+4 is a prime number
(2) n+3 is not a prime number.



Answer: A

please help.
1. All the prime numbers except 2 are odd. In this case n is not equal to 2 anyway, sufficient to conclude that n is odd
2. n+3 is not a prime number is not sufficient (7+3, 6+3 both are not prime) to decide whether n is prime or not

Hence A
Always borrow money from a pessimist, he doesn't expect to be paid back.
Top
Junior | Next Rank: 30 Posts
Posts: 26
Joined: Tue Sep 22, 2009 8:25 pm

by rdchandvadkar » Tue Feb 09, 2010 12:35 pm
thanks a lot for the responses..
Top
User avatar
Legendary Member
Posts: 1132
Joined: Mon Jul 20, 2009 3:38 am
Location: India
Thanked: 64 times
Followed by:6 members
GMAT Score:760

by harsh.champ » Tue Feb 09, 2010 1:53 pm
rdchandvadkar wrote:Is the positive integer n an odd integer?

(1) n+4 is a prime number
(2) n+3 is not a prime number.



Answer: A

please help.
Important pt. :-All the prime no.s are odd except 2.

1:- n+4=prime ,hence n = odd - even = odd Sufficient.
2:- n+3=not prime , but it can be 9 as well as 8 .Hence insufficient.

The OA should be A.
It takes time and effort to explain, so if my comment helped you please press Thanks button :)



Just because something is hard doesn't mean you shouldn't try,it means you should just try harder.

"Keep Walking" - Johnny Walker :P
Top
Post new topic Post Reply
• Page 1 of 1