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

    Available with Beat the GMAT members only code

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

    Available with Beat the GMAT members only code

    MORE DETAILS
    PrepScholar GMAT
  • Veritas Prep
    Free Veritas GMAT Class
    Experience Lesson 1 Live Free

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas 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
  • 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

in costume for Halloween

This topic has 2 expert replies and 0 member replies

GMAT/MBA Expert

sanju09 GMAT Instructor
Joined
21 Jan 2009
Posted:
3650 messages
Followed by:
81 members
Thanked:
267 times
GMAT Score:
760

in costume for Halloween

Post Mon Sep 09, 2013 11:47 pm
Elapsed Time: 00:00
  • Lap #[LAPCOUNT] ([LAPTIME])
    What percentage of the current fourth graders at Liberation Elementary School dressed in costume for Halloween for the past two years in a row (both this year and last year)?
    (1) 60% of the current fourth graders at Liberation Elementary School dressed in costume for Halloween this year.
    (2) Of the current fourth graders at Liberation Elementary School who did not dress in costume for Halloween this year, 80% did not dress in costume last year.


    Source: The Princeton Review

    www.manyagroup.com

    _________________
    The mind is everything. What you think you become. –Lord Buddha



    Sanjeev K Saxena
    Quantitative Instructor
    The Princeton Review - Manya Abroad
    Lucknow-226001

    www.manyagroup.com

    Free GMAT Practice Test How can you improve your test score if you don't know your baseline score? Take a free online practice exam. Get started on achieving your dream score today! Sign up now.
    Post Tue Sep 10, 2013 6:33 am
    sanju09 wrote:
    What percentage of the current fourth graders at Liberation Elementary School dressed in costume for Halloween for the past two years in a row (both this year and last year)?

    (1) 60% of the current fourth graders at Liberation Elementary School dressed in costume for Halloween this year.

    (2) Of the current fourth graders at Liberation Elementary School who did not dress in costume for Halloween this year, 80% did not dress in costume last year.
    It may be useful to use the Double Matrix Method to help us arrange our information. This technique can be used for most questions featuring a population in which each member has two characteristics associated with it.
    Here, we have a population of fourth graders, and the two characteristics are:
    - costume this year or no costume last year
    - costume last year or no costume last year

    Since our goal is to find a certain percent, let's say that we have a population of 100 students. So, we get the following:
    ttp://postimg.org/image/r1y1gm6rr/" target="_blank">
    To learn more about the Double Matrix Method, watch our free video: http://www.gmatprepnow.com/module/gmat-word-problems?id=919
    Notice that I've placed a star in the top-left corner (dressed last year AND this year) to denote which box we need to answer our target question.

    Target question: What percentage of the fourth graders dressed in costume both this year and last year

    Statement 1: 60% of the current fourth graders at Liberation Elementary School dressed in costume for Halloween this year
    Since we're saying that the total population is 100, there were 60 students who dressed in costume this year. This means that there were 40 students who did NOT dress in costume this year
    We get:
    ttp://postimg.org/image/hwpomr3d3/" target="_blank">
    We still don't have enough information to determine the number of students in the top-left box, so we cannot answer the target question with certainty.
    Statement 1 is NOT SUFFICIENT

    Statement 2: Of the current fourth graders at Liberation Elementary School who did not dress in costume for Halloween this year, 80% did not dress in costume last year.
    If we let x = # of students who did NOT dress in costume for Halloween this year, then 0.8x represents the # of students who ALSO did not dress in costume last year.
    ttp://postimg.org/image/dz2excgjr/" target="_blank">
    We still don't have enough information to determine the number of students in the top-left box, so we cannot answer the target question with certainty.
    Statement 2 is NOT SUFFICIENT


    Statements 1 and 2 combined
    Statement 1 tells us that 40 students did NOT dress in costume this year
    Statement 2 tells us that 80% of those 40 students also did NOT dress in costume LAST year.
    So, 32 students did not dress in costume for both years (which means 8 students dressed last year but not this year). We get:
    ttp://postimg.org/image/sktflldc7/" target="_blank">
    We still don't have enough information to determine the number of students in the top-left box, so we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT

    Answer = E

    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

    Thanked by: sanju09, gmattesttaker2
    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!
    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 lheiannie07 111 topics
    2 ardz24 64 topics
    3 LUANDATO 62 topics
    4 swerve 60 topics
    5 AAPL 57 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 EconomistGMATTutor

    The Economist GMAT Tutor

    130 posts
    3 image description Rich.C@EMPOWERgma...

    EMPOWERgmat

    122 posts
    4 image description GMATGuruNY

    The Princeton Review Teacher

    122 posts
    5 image description Scott@TargetTestPrep

    Target Test Prep

    118 posts
    See More Top Beat The GMAT Experts