• Target Test Prep
    5-Day Free Trial
    5-day free, full-access trial TTP Quant

    Available with Beat the GMAT members only code

    MORE DETAILS
    Target Test Prep
  • Varsity Tutors
    Award-winning private GMAT tutoring
    Register now and save up to $200

    Available with Beat the GMAT members only code

    MORE DETAILS
    Varsity Tutors
  • PrepScholar GMAT
    5 Day FREE Trial
    Study Smarter, Not Harder

    Available with Beat the GMAT members only code

    MORE DETAILS
    PrepScholar GMAT
  • Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

    MORE DETAILS
    Magoosh
  • EMPOWERgmat Slider
    1 Hour Free
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • Kaplan Test Prep
    Free Practice Test & Review
    How would you score if you took the GMAT

    Available with Beat the GMAT members only code

    MORE DETAILS
    Kaplan Test Prep
  • e-gmat Exclusive Offer
    Get 300+ Practice Questions
    25 Video lessons and 6 Webinars for FREE

    Available with Beat the GMAT members only code

    MORE DETAILS
    e-gmat Exclusive Offer
  • Veritas Prep
    Free Veritas GMAT Class
    Experience Lesson 1 Live Free

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas Prep
  • Economist Test Prep
    Free Trial & Practice Exam
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist Test Prep

OG12 #106: if x and y are integers, is xy even?

This topic has 2 expert replies and 5 member replies
Fractal Master | Next Rank: 500 Posts Default Avatar
Joined
22 Aug 2010
Posted:
183 messages
Thanked:
5 times
Test Date:
24.09.2011
Target GMAT Score:
700

OG12 #106: if x and y are integers, is xy even?

Post Wed Sep 15, 2010 6:46 am
Elapsed Time: 00:00
  • Lap #[LAPCOUNT] ([LAPTIME])
    if x and y are integers, is xy even?

    (1) x = y + 1
    (2) x/y is an even integer

    according to og, the solution is: D

    Why is (1) sufficient? I mean, x could be 1 and y could be 0 --> xy would not be even, because xy = 0! but x could also be 2 and y=1, then xy=2 which is even! so for me, (1) is insufficient!

    ?

    thx for hlp

    Need free GMAT or MBA advice from an expert? Register for Beat The GMAT now and post your question in these forums!
    beatthegmatinsept Master | Next Rank: 500 Posts
    Joined
    09 Aug 2010
    Posted:
    422 messages
    Followed by:
    1 members
    Thanked:
    22 times
    Test Date:
    September 25, 2010
    Target GMAT Score:
    650+
    GMAT Score:
    680
    Post Wed Sep 15, 2010 7:43 am
    Fractal wrote:
    if x and y are integers, is xy even?

    (1) x = y + 1
    (2) x/y is an even integer

    according to og, the solution is: D

    Why is (1) sufficient? I mean, x could be 1 and y could be 0 --> xy would not be even, because xy = 0! but x could also be 2 and y=1, then xy=2 which is even! so for me, (1) is insufficient!

    ?

    thx for hlp
    Your logic on (a) is correct, except that in the only scenario where you get 0 as xy, that qualifies as an even integer as well. 0 is never considered odd, its considered even. I just googled it to confirm Smile

    _________________
    Being defeated is often only a temporary condition. Giving up is what makes it permanent.

    selango Legendary Member
    Joined
    29 Dec 2009
    Posted:
    1460 messages
    Followed by:
    7 members
    Thanked:
    135 times
    Post Wed Sep 15, 2010 7:52 am
    Fractal wrote:
    if x and y are integers, is xy even?

    (1) x = y + 1
    (2) x/y is an even integer

    according to og, the solution is: D

    Why is (1) sufficient? I mean, x could be 1 and y could be 0 --> xy would not be even, because xy = 0! but x could also be 2 and y=1, then xy=2 which is even! so for me, (1) is insufficient!

    ?

    thx for hlp
    Check the properties for integer Zero in OG.

    0 is even integer.

    0 is neither positive nor odd.

    _________________
    --Anand--

    Fractal Master | Next Rank: 500 Posts Default Avatar
    Joined
    22 Aug 2010
    Posted:
    183 messages
    Thanked:
    5 times
    Test Date:
    24.09.2011
    Target GMAT Score:
    700
    Post Wed Sep 15, 2010 7:53 am
    thx a lot

    and i am sorry for that question. i should have known it! i just looked it up in kaplan; 0 is even!

    buzzdeepak Senior | Next Rank: 100 Posts Default Avatar
    Joined
    17 Sep 2012
    Posted:
    56 messages
    Followed by:
    1 members
    Thanked:
    13 times
    GMAT Score:
    710
    Post Sat Dec 29, 2012 4:06 am
    What if x=2 and y=4?

    OG solution says they are consecutive but the question doesn't state that....

    IMO Ans= B.

    Post Sat Dec 29, 2012 6:58 am
    Fractal wrote:
    if x and y are integers, is xy even?

    (1) x = y + 1
    (2) x/y is an even integer

    When posting questions, please use the spoiler function to hide the correct answer. This will allow others to attempt the question without seeing the final answer.

    Target question: Is xy even?

    Aside: For xy to be even, we need x to be even, or y to be even (or both even).

    Statement 1: x = y+1
    This tells us that x is 1 greater than y.
    This means that x and y are consecutive integers.
    If x and y are consecutive integers, then one must be odd and the other must be even.
    As such, the product xy must be even.
    So, statement 1 is SUFFICIENT

    Statement 2: x/y is an even integer.
    If x/y is an even integer, then we can write x/y = 2k (where k is an integer)
    Now take the equation and multiply both sides by y to get: x = 2ky
    If k and y are both integers, we can see that 2ky (also known as x) must be even.
    If x is even, then the product xy must be even.
    So, statement 2 is SUFFICIENT

    Answer = D

    Cheers,
    Brent

    _________________
    Brent Hanneson – Founder of GMATPrepNow.com
    Use our video course along with Beat The GMAT's free 60-Day Study Guide

    Check out the online reviews of our course

    GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMAT’s FREE 60-Day Study Guide and reach your target score in 2 months!
    kaiweiweiwei Junior | Next Rank: 30 Posts
    Joined
    07 Aug 2012
    Posted:
    14 messages
    Post Sun Dec 30, 2012 5:54 pm
    If y=0 and x=1, is xy still even?

    I forget if 0 is even or not.

    Post Sun Dec 30, 2012 5:58 pm
    0 is, indeed, even.

    Cheers,
    Brent

    _________________
    Brent Hanneson – Founder of GMATPrepNow.com
    Use our video course along with Beat The GMAT's free 60-Day Study Guide

    Check out the online reviews of our course

    GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMAT’s FREE 60-Day Study Guide and reach your target score in 2 months!

    Best Conversation Starters

    1 Vincen 180 topics
    2 lheiannie07 61 topics
    3 Roland2rule 61 topics
    4 ardz24 40 topics
    5 VJesus12 14 topics
    See More Top Beat The GMAT Members...

    Most Active Experts

    1 image description Brent@GMATPrepNow

    GMAT Prep Now Teacher

    160 posts
    2 image description Rich.C@EMPOWERgma...

    EMPOWERgmat

    102 posts
    3 image description GMATGuruNY

    The Princeton Review Teacher

    99 posts
    4 image description Jay@ManhattanReview

    Manhattan Review

    86 posts
    5 image description Matt@VeritasPrep

    Veritas Prep

    80 posts
    See More Top Beat The GMAT Experts