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

    Available with Beat the GMAT members only code

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

    Available with Beat the GMAT members only code

    MORE DETAILS
    PrepScholar GMAT
  • 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
  • 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
  • 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

David has d books (OG16)

This topic has 2 expert replies and 0 member replies
boomgoesthegmat Senior | Next Rank: 100 Posts Default Avatar
Joined
25 Apr 2016
Posted:
93 messages
Thanked:
1 times

David has d books (OG16)

Post Thu May 19, 2016 3:45 pm
Elapsed Time: 00:00
  • Lap #[LAPCOUNT] ([LAPTIME])
    David has d books, which is 3 times as many as Jeff and 1/2 as many as Paula. How many books do the three of them have altogether, in terms of d ?

    A) (5/6)d
    B) (7/3)d
    C) (10/3)d
    D) (7/2)d
    E) (9/2)d

    OA: C



    Last edited by boomgoesthegmat on Thu May 19, 2016 4:30 pm; edited 1 time in total

    Need free GMAT or MBA advice from an expert? Register for Beat The GMAT now and post your question in these forums!
    Post Thu May 19, 2016 4:28 pm
    Hi boomgoesthegmat,

    To start, there's a typo in your transcription - it's supposed to read "...and 1/2 as many as Paula...."

    We can answer this question by TESTing VALUES or by doing algebra...

    IF...
    Jeff = 2 books
    David = 6 books = D books
    Paula = 12 books

    The total number of books = 2+6+12 = 20

    So we're looking for an answer that equals 20 when D=6. There's only one answer that matches...

    Final Answer: C

    GMAT assassins aren't born, they're made,
    Rich

    _________________
    Contact Rich at Rich.C@empowergmat.com

    Post Fri May 20, 2016 9:01 am
    boomgoesthegmat wrote:
    David has d books, which is 3 times as many as Jeff and 1/2 as many as Paula. How many books do the three of them have altogether, in terms of d ?

    A) (5/6)d
    B) (7/3)d
    C) (10/3)d
    D) (7/2)d
    E) (9/2)d

    OA: C
    Rich has demonstrated the INPUT-OUTPUT approach. Here's an algebraic approach.

    d = # of books that David has

    David has 3 times as many books as Jeff
    So, d/3 = # of books that Jeff has

    David has 1/2 as many books as Paula
    So, 2d = # of books that Paula has

    How many books do the three of them have altogether, in terms of d ?
    TOTAL # of books = d + d/3 + 2d
    = 3d/3 + d/3 + 6d/3
    = 10d/3
    = C

    ---------------------------------

    Rich and I have demonstrated the two methods (Algebraic and Input-Output) for solving a question type I call Variables in the Answer Choices.
    If you'd like more information on these approaches, we have some videos:
    - Variables in the Answer Choices - http://www.gmatprepnow.com/module/gmat-word-problems/video/933
    - Tips for the Algebraic Approach - http://www.gmatprepnow.com/module/gmat-word-problems/video/934
    - Tips for the Input-Output Approach - http://www.gmatprepnow.com/module/gmat-word-problems/video/935

    Here are some more questions to practice with:
    - http://www.beatthegmat.com/what-mistake-am-i-making-in-this-substitution-last-sunday-a-t276293.html
    - http://www.beatthegmat.com/car-dealer-sales-t274136.html
    - http://www.beatthegmat.com/ps-rate-times-t276107.html
    - http://www.beatthegmat.com/to-find-the-least-perfect-square-t273338.html
    - http://www.beatthegmat.com/y-dollars-from-the-rental-venture-t273031.html
    - http://www.beatthegmat.com/meters-in-x-minutes-t273854.html
    - http://www.beatthegmat.com/a-better-explanation-please-t279396.html


    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
    Come see all of our free resources

    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