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

Redeem

OG11 Question 153

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Newbie | Next Rank: 10 Posts
Posts: 8
Joined: Wed Apr 30, 2008 6:23 pm

OG11 Question 153

by cliou21 » Fri May 09, 2008 1:33 pm
Can someone please explain this better then the OG?

153. Does the integer k have a factor p such that 1>p>k?
(1) k>4!
(2) 13! + 2 <= k <= 13! + 13

I understand that (1) is not sufficient.
With (2), how can you be sure that k is not a prime number between 13!+2 and 13! + 13?

Thanks!
Top
Source: — Data Sufficiency |
User avatar
Legendary Member
Posts: 986
Joined: Wed Dec 20, 2006 11:07 am
Location: India
Thanked: 51 times
Followed by:1 members

Re: OG11 Question 153

by gabriel » Tue May 13, 2008 11:56 am
cliou21 wrote:Can someone please explain this better then the OG?

153. Does the integer k have a factor p such that 1>p>k?
(1) k>4!
(2) 13! + 2 <= k <= 13! + 13

I understand that (1) is not sufficient.
With (2), how can you be sure that k is not a prime number between 13!+2 and 13! + 13?

Thanks!
K will never be a prime number if it is an integer between 13!+2 and 13!+13. Here is why. 13! (= 1*2*3*...*12*13) is a multiple of every number between 1 and 13 i.e every number between 1 and 13 is a factor of 13!. If there is a number of the type 13!+a and if "a" is contained in 13! (By that I mean it is one of the integer between 1 and 13,) then "a" will be a factor of 13!+a. In the above question "a" assumes values between 2 and 13, all of which are a part of 13!. Hence the integers between 13!+2 and 13!+13 are not prime. Let me know if you have any doubts.

Regards
Top
Newbie | Next Rank: 10 Posts
Posts: 8
Joined: Wed Apr 30, 2008 6:23 pm

by cliou21 » Wed May 14, 2008 11:24 am
Thanks! This helps alot! :D
Top
Master | Next Rank: 500 Posts
Posts: 132
Joined: Fri Sep 05, 2008 10:19 pm
Location: Bangladesh
Thanked: 1 times

Re: OG11 Question 153

by rabab » Fri Oct 17, 2008 6:55 am
gabriel wrote:If there is a number of the type 13!+a and if "a" is contained in 13! (By that I mean it is one of the integer between 1 and 13,) then "a" will be a factor of 13!+a.
Dear Gabriel

Could you pls explain the line above? I am having difficulty understanding this particular problem.
Top
Post new topic Post Reply
• Page 1 of 1