January 21, 2019 January 21, 2019 10:00 PM PST 11:00 PM PST Mark your calendars  All GMAT Club Tests are free and open January 21st for celebrate Martin Luther King Jr.'s Birthday. January 22, 2019 January 22, 2019 10:00 PM PST 11:00 PM PST In case you didn’t notice, we recently held the 1st ever GMAT game show and it was awesome! See who won a full GMAT course, and register to the next one.
Author 
Message 
TAGS:

Hide Tags

Intern
Joined: 08 May 2014
Posts: 10
Concentration: General Management, Operations

If x is a positive integer, is (10x  1) divisible by y
[#permalink]
Show Tags
14 Nov 2014, 09:35
Question Stats:
52% (01:46) correct 48% (01:48) wrong based on 87 sessions
HideShow timer Statistics
If x is a positive integer, is (10x  1) divisible by y (1) x is a multiple of y (2) y is a prime number
Official Answer and Stats are available only to registered users. Register/ Login.



Intern
Joined: 23 Oct 2012
Posts: 44

Re: If x is a positive integer, is (10x  1) divisible by y
[#permalink]
Show Tags
14 Nov 2014, 22:08
prakash85 wrote: If x is a positive integer, is (10x  1) divisible by y
(1) x is a multiple of y (2) y is a prime number Q asks (10x1)/y 1) x/y x=3 , y=0.5 yes x=4, y=2 no insufficient 2) y is a prime number. insufficient 1+ 2 x=4, y=2 no x=10, y=5 no x=20, y = 4 no sufficient. Thus, OA is C.
_________________
Kudos please!



Director
Affiliations: GMATQuantum
Joined: 19 Apr 2009
Posts: 612

Re: If x is a positive integer, is (10x  1) divisible by y
[#permalink]
Show Tags
14 Nov 2014, 22:51
I would suggest that a proper GMAT question on divisibility will constrain y to be an integer. I have never seen a GMAT question that is related to factors and divisibility where a variable could be a real number.
The modified question should look like: If x and y are positive integers, is (10x  1) divisible by y ?
(1) x is a multiple of y (2) y is a prime number
Cheers, Dabral



Manager
Joined: 22 Sep 2012
Posts: 129
Concentration: Strategy, Technology
WE: Information Technology (Computer Software)

Re: If x is a positive integer, is (10x  1) divisible by y
[#permalink]
Show Tags
15 Nov 2014, 08:00
Statement 1: x is a multiple of y x = n* y Now, the question becomes is 10*n*y1 is divisible by y Case 1: Answer is yes, if y is 1. Case 2: Answer is no, if the y is any number other than 1 [ This is true from the theory of Coprimes i.e Two consecutive number are coprime meaning donot share any common factor except 1. Same holds true if one is multiple of the other ] Therefore insufficient
Statement 2: y is a prime number y can be 2, 3 5, 7 etc Insufficient
Combining 1 and 2: we can say only the case 2 remains. And therefore using both statements together we can solve the problem. Answer C)



NonHuman User
Joined: 09 Sep 2013
Posts: 9459

Re: If x is a positive integer, is (10x  1) divisible by y
[#permalink]
Show Tags
27 Jan 2018, 01:43
Hello from the GMAT Club BumpBot! Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up  doing my job. I think you may find it valuable (esp those replies with Kudos). Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
GMAT Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources




Re: If x is a positive integer, is (10x  1) divisible by y &nbs
[#permalink]
27 Jan 2018, 01:43






