Find all School-related info fast with the new School-Specific MBA Forum

It is currently 21 Oct 2014, 12:32

Close

GMAT 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

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If x,y,z are positive integers,and x!+x/z=y,then what is the

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Director
Director
User avatar
Joined: 25 Oct 2008
Posts: 609
Location: Kolkata,India
Followers: 9

Kudos [?]: 192 [0], given: 100

If x,y,z are positive integers,and x!+x/z=y,then what is the [#permalink] New post 22 Jul 2009, 05:17
1
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
If x,y,z are positive integers,and x!+x/z=y,then what is the value of z?
1. x is a factor of y
2. z<x

Guys,plugging in got me no where..Ijust went blindly plugging in random nos,didnt succeed and ended up getting the answer wrong.any ideas?
_________________

countdown-beginshas-ended-85483-40.html#p649902

1 KUDOS received
Senior Manager
Senior Manager
avatar
Joined: 23 Jun 2009
Posts: 359
Location: Turkey
Schools: UPenn, UMich, HKS, UCB, Chicago
Followers: 5

Kudos [?]: 95 [1] , given: 60

Re: x,y,z are positive integers [#permalink] New post 22 Jul 2009, 05:38
1
This post received
KUDOS
1 is suff.
y = 1.2.3....x + x/z
y= x( 1.2.3..(x-1)+1/z) so if x is a factor of y then 1/z must be integer so z=1

2 is insuff.
since x! is integer and y is integer x/z must be integer. And x>=z. This only says that x is not equal to z. We can not find the value of z.

So answer is A.
Manager
Manager
User avatar
Joined: 03 Jul 2009
Posts: 107
Location: Brazil
Followers: 3

Kudos [?]: 52 [0], given: 13

Re: x,y,z are positive integers [#permalink] New post 22 Jul 2009, 05:54
I got A as well

y = 1*2*3*4*...*x + x/z
y = x*(1/z + 1*2*3*4*...)
y/x = 1/z + 1*2*3*4 ------->> Final Expression

1) Since y/x and 1*2*3*4*... are both integers, then 1/z must be integer. The only value for z, such as 1/z is an integer is 1. Thus SUFF.

2) Using the same final expression, the fact that z<x does not help in anything.

A.
Director
Director
User avatar
Joined: 25 Oct 2008
Posts: 609
Location: Kolkata,India
Followers: 9

Kudos [?]: 192 [0], given: 100

Re: x,y,z are positive integers [#permalink] New post 23 Jul 2009, 01:18
Guys OA is C.Could somebody please explain?
_________________

countdown-beginshas-ended-85483-40.html#p649902

Senior Manager
Senior Manager
avatar
Joined: 23 Jun 2009
Posts: 359
Location: Turkey
Schools: UPenn, UMich, HKS, UCB, Chicago
Followers: 5

Kudos [?]: 95 [0], given: 60

Re: x,y,z are positive integers [#permalink] New post 23 Jul 2009, 01:32
I don't think the answer is C. I think the OA is wrong.
Manager
Manager
avatar
Joined: 15 Apr 2008
Posts: 50
Location: Moscow
Followers: 0

Kudos [?]: 12 [0], given: 8

Re: x,y,z are positive integers [#permalink] New post 23 Jul 2009, 03:36
Initially have chosen A as well, but... on the second thought it's really C:
x!+\frac{x}{z}=y
x*((x-1)!+\frac{1}{z})=y

x*(\frac{(x-1)!*z+1}{z})=y

z can be any integer, provided x=z, which makes St1 insufficient, we need St2.
Senior Manager
Senior Manager
avatar
Joined: 23 Jun 2009
Posts: 359
Location: Turkey
Schools: UPenn, UMich, HKS, UCB, Chicago
Followers: 5

Kudos [?]: 95 [0], given: 60

Re: x,y,z are positive integers [#permalink] New post 23 Jul 2009, 04:18
No. z can not be any integer.

Based on the equation you found; if x = z then equation becomes (x! + 1). But x can only be the factor of y when the value of x = 1, z=1 and y=2. In other values of x; x can not be a factor of y because x! and x!+1 are coprimes (numbers that do not have any divisors other than 1). So z becomes 1 ;) We can find z.
Manager
Manager
avatar
Joined: 15 Apr 2008
Posts: 50
Location: Moscow
Followers: 0

Kudos [?]: 12 [0], given: 8

Re: x,y,z are positive integers [#permalink] New post 23 Jul 2009, 04:59
maliyeci wrote:
No. z can not be any integer.

Based on the equation you found; if x = z then equation becomes (x! + 1). But x can only be the factor of y when the value of x = 1, z=1 and y=2. In other values of x; x can not be a factor of y because x! and x!+1 are coprimes (numbers that do not have any divisors other than 1). So z becomes 1 ;) We can find z.

Agree with you. Have totally missed the condition that x is a factory of y.
Re: x,y,z are positive integers   [#permalink] 23 Jul 2009, 04:59
    Similar topics Author Replies Last post
Similar
Topics:
3 Experts publish their posts in the topic What is the value of x/(yz) ? Bunuel 5 14 Feb 2014, 01:04
2 Experts publish their posts in the topic What is the value of xyz? suk1234 4 26 Dec 2013, 09:45
Experts publish their posts in the topic What is the perimeter of right triangle XYZ? ereyhan 4 24 Jan 2013, 16:22
Experts publish their posts in the topic What is the value of x/yz? financeguy25 7 08 Mar 2009, 18:28
7 Experts publish their posts in the topic What is the ratio of x:y:z? lumone 10 27 Nov 2007, 07:17
Display posts from previous: Sort by

If x,y,z are positive integers,and x!+x/z=y,then what is the

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.