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

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist Test Prep
  • The Princeton Review
    FREE GMAT Exam
    Know how you'd score today for $0

    Available with Beat the GMAT members only code

    MORE DETAILS
    The Princeton Review
  • 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
  • Veritas Prep
    Free Veritas GMAT Class
    Experience Lesson 1 Live Free

    Available with Beat the GMAT members only code

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

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

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

    Available with Beat the GMAT members only code

    MORE DETAILS
    PrepScholar GMAT

If x and y are positive integers is y odd?

This topic has 1 expert reply and 0 member replies

If x and y are positive integers is y odd?

Post Thu Nov 30, 2017 9:29 am
If x and y are positive integers, is y odd?

(1) (y+2)!/x! = odd
(2) (y+2)!/x! is greater than 2

The OA is C .

I am confuse here. Experts, may you give me some help? Thanks in advance.

  • +1 Upvote Post
  • Quote
  • Flag
Post Thu Nov 30, 2017 10:15 pm
VJesus12 wrote:
If x and y are positive integers, is y odd?

(1) (y+2)!/x! = odd
(2) (y+2)!/x! is greater than 2

The OA is C .

I am confuse here. Experts, may you give me some help? Thanks in advance.
(1) (y+2)!/x! = odd

Case 1: Say y = 1 (Odd) and x = 2, then (y+2)!/x! = (1+2)!/2! = 3!/2! = 1.2.3/1.2 = 3 (Odd).
Case 2: Say y = 2 (Even) and x = 4, then (y+2)!/x! = (2+2)!/4! = 4!/4! = 1 (Odd).

No unique answer. Insufficient

(2) (y+2)!/x! is greater than 2

Case 1: Say y = 1 (Odd) and x = 2, then (y+2)!/x! = (1+2)!/2! = 3!/2! = 1.2.3/1.2 = 3 >2.
Case 2: Say y = 2 (Even) and x = 1, then (y+2)!/x! = (2+2)!/1! = 4!/1! = 1.2.3.4/1 = 12 >2.

No unique answer. Insufficient

(1) and (2) together

Case 2 of Statement is not a valid case as 1 is not greater than 2, while Case 2 of Statement 2 is also not valid as 12 is not odd.

When we have y odd and x - y = 1, the value of (y+2)!/x! would be odd and greater than 2. Sufficient.

Say y = 3 (Odd) and x = 4, then (y+2)!/x! = (3+2)!/4! = 5!/4! = 1.2.3.4.5/1.2.3.4 = 5 >2.

The correct answer: C

Hope this helps!

-Jay
_________________
Manhattan Review GMAT Prep

Locations: New York | New Delhi | Seoul | Cairo | and many more...

Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.

  • +1 Upvote Post
  • Quote
  • Flag

Top First Responders*

1 GMATGuruNY 65 first replies
2 Rich.C@EMPOWERgma... 46 first replies
3 Brent@GMATPrepNow 41 first replies
4 Jay@ManhattanReview 24 first replies
5 Terry@ThePrinceto... 10 first replies
* Only counts replies to topics started in last 30 days
See More Top Beat The GMAT Members

Most Active Experts

1 image description GMATGuruNY

The Princeton Review Teacher

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

EMPOWERgmat

114 posts
3 image description Jeff@TargetTestPrep

Target Test Prep

98 posts
4 image description Scott@TargetTestPrep

Target Test Prep

92 posts
5 image description Max@Math Revolution

Math Revolution

89 posts
See More Top Beat The GMAT Experts