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

    Available with Beat the GMAT members only code

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

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist 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
  • Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

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

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • 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

OG 18, question - 395

This topic has 2 expert replies and 0 member replies

OG 18, question - 395

Post Wed Sep 20, 2017 11:20 pm
Elapsed Time: 00:00
  • Lap #[LAPCOUNT] ([LAPTIME])
    Are all of the numbers in a certain list of 15 numbers equal?
    (1) The sum of all the numbers in the list is 60.
    (2) The sum of any 3 numbers in the list is 12.

    Need free GMAT or MBA advice from an expert? Register for Beat The GMAT now and post your question in these forums!
    Post Thu Sep 21, 2017 12:04 am
    vaibhav101 wrote:
    Are all of the numbers in a certain list of 15 numbers equal?

    (1) The sum of all the numbers in the list is 60.
    (2) The sum of any 3 numbers in the list is 12.
    Statement 1: The sum of all the numbers in the list is 60.

    Clearly insufficient.

    Statement 2: The sum of any 3 numbers in the list is 12.

    Since the sum of any three numbers is 12, all numbers must equal, because if they are not equal, then we could pick a set of three numbers such that their sum is not 12. Sufficient.

    The correct answer: B

    Hope this helps!

    Download free ebook: Manhattan Review GMAT Quantitative Question Bank Guide

    -Jay
    _________________
    Manhattan Review GMAT Prep

    Locations: New York | Hyderabad | Mexico City | Toronto | and many more...

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

    Thanked by: vaibhav101
    Post Thu Sep 21, 2017 5:35 am
    Quote:
    Are all of the numbers in a certain list of 15 numbers equal?

    (1) The sum of all the numbers in the list is 60.
    (2) The sum of any 3 numbers in the list is 12.
    Target question: Are all 15 numbers equal?

    Statement 1: The sum of all the numbers in the list is 60.
    There are several possible scenarios that satisfy this statement. Here are two.
    Case a: numbers are: {4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4}, in which case all of the numbers are equal
    Case b: numbers are: {4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 1, 7}, in which case all of the numbers are not equal
    Statement 1 is NOT SUFFICIENT

    Statement 2: The sum of any 3 numbers in the list is 12.
    This is a very powerful statement, because it tells us that all of the numbers in the set are equal.
    Let's let a,b,c and d be four of the 15 numbers in the set.
    We know that a + b + c = 12
    Notice that if I replace ANY of these three values (a,b or c) with d, the sum must still be 12.
    This tells us that a, b and c must all equal d.
    I can use a similar approach to show that e, f and g must also equal d.
    In fact, I can show that ALL of the numbers in the set must equal d, which means all of the numbers in the set must be equal.
    Since we can answer the target question with certainty, statement 2 is SUFFICIENT

    Answer = B

    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 54 topics
    4 ardz24 44 topics
    5 VJesus12 14 topics
    See More Top Beat The GMAT Members...

    Most Active Experts

    1 image description Brent@GMATPrepNow

    GMAT Prep Now Teacher

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

    EMPOWERgmat

    105 posts
    3 image description GMATGuruNY

    The Princeton Review Teacher

    101 posts
    4 image description Jay@ManhattanReview

    Manhattan Review

    82 posts
    5 image description Matt@VeritasPrep

    Veritas Prep

    80 posts
    See More Top Beat The GMAT Experts