GMATPREP EXAM 1 (2)

Oldest

Best Reply

Author

Message

TAGS:

Intern

Joined: 03 Dec 2006

Posts: 15

Followers: 0

Kudos [?]: 0 [0], given: 0

GMATPREP EXAM 1 (2) [#permalink]

18 Sep 2007, 22:23

Can someone explain the logic in this question? How do you approach this divisibility question and all other for that matter?

thanks

Attachments

GMP 3.JPG [ 70.49 KiB | Viewed 253 times ]

CEO

Joined: 29 Mar 2007

Posts: 2618

Followers: 13

Kudos [?]: 142 [0], given: 0

[#permalink]

18 Sep 2007, 23:56

This one took me quite a bit of time =( bout 3 1/2 min. thats no good.

Owell.

rewrite the statment like this n^2-1/24.

Then _____
24|n^2-1 (if this doesn't show the way I want it to, essentially, use the long division box)

S1: since n cant be divisible by 2 try values for n that arent divisible by 2.

5^2 =25. ---> 25-1/24 R here will be 0

Try now finding a value you know won't be divisible by 24.

9^2 81-1/24 this is def. not going to have a R of 0. So insuff.

S2:
cannot be divisible by 3. So again try 5^2-1/24 R=0.

Try finding a value that u know won't leave a R of 0.

10^2-1/24 99/24 Def R does not equal 0.

S1&S2:
Realize here that the following values for n are not possible: 2,3,4,6,8,9,10 and anything divisible by 2 or 3! So this essentially leaves primes of 5,7,11,13 etc...

Try a couple and determine ans from here as I was already at 3min!

Try a few values to see if this works again 5^2-1/24 24/24 R=0

7^2-1/24 R=0.

11^2-1/24 R=0.

Ans C.

Director

Joined: 09 Aug 2006

Posts: 776

Followers: 1

Kudos [?]: 18 [0], given: 0

Re: GMATPREP EXAM 1 (2) [#permalink]

18 Sep 2007, 23:56

ericuva wrote:

Can someone explain the logic in this question? How do you approach this divisibility question and all other for that matter?

thanks

I plugged in numbers to solve this one.

Stat 1: if n=3 remainder = 0, if n=9 remainder=1, Insuff.

Stat 2: if n=5, remainder=0, if n=10, remainder=3, Insuff.

Stat 1 & 2: n=5, 7, 11, 13, remainder = 0.

Answer C.

Re: GMATPREP EXAM 1 (2) [#permalink] 18 Sep 2007, 23:56

	Similar topics	Author	Replies	Last post
Similar Topics:	GMATPREP EXAM 1 (1)	ericuva	4	18 Sep 2007, 22:21
	GMATPREP EXAM 1 (3)	ericuva	2	18 Sep 2007, 22:24
	GMATPREP EXAM 1 (5)	ericuva	1	18 Sep 2007, 22:28
	GMATPREP EXAM 1 (6)	ericuva	6	18 Sep 2007, 22:31
	GMATPrep 2.1 no way to access practice exam questions?	kcw984	2	17 Jun 2012, 09:11

GMATPREP EXAM 1 (2)

Main navigation

GMAT Resources

Partners

MBA Resources

GMAT ® is a registered trademark of the Graduate Management Admission Council ® (GMAC ®). GMAT Club's website has not been reviewed or endorsed by GMAC.

GMAT Courses

Admissions Consulting

GMATPREP EXAM 1 (2)

GMATPREP EXAM 1 (2)

Main navigation

GMAT Resources

Partners

MBA Resources