• 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
  • 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
  • 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
  • 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
  • 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

Difficult Math Question #33 - Probability

This topic has 4 member replies
800guy Master | Next Rank: 500 Posts Default Avatar
Joined
27 Jun 2006
Posted:
354 messages
Followed by:
5 members
Thanked:
11 times

Difficult Math Question #33 - Probability

Post Mon Oct 23, 2006 2:27 pm
Elapsed Time: 00:00
  • Lap #[LAPCOUNT] ([LAPTIME])
    A number is selected at random from first 30 natural numbers. What is the probability that the number is a multiple of either 3 or 13?

    (A) 17/30
    (B) 2/5
    (C) 7/15
    (D) 4/15
    (E) 11/30

    Need free GMAT or MBA advice from an expert? Register for Beat The GMAT now and post your question in these forums!
    rajs.kumar Senior | Next Rank: 100 Posts Default Avatar
    Joined
    09 Jun 2006
    Posted:
    87 messages
    Thanked:
    2 times
    Post Tue Oct 24, 2006 2:49 am
    2/5.

    10 multiples of 3 and 2 multiples of 13 adding to a total of 12. So the probability is 12/30.

    ajith Legendary Member
    Joined
    21 Sep 2006
    Posted:
    1275 messages
    Followed by:
    2 members
    Thanked:
    124 times
    Test Date:
    April 2010
    Target GMAT Score:
    740
    Post Tue Oct 24, 2006 8:34 pm
    rajs.kumar wrote:
    2/5.

    10 multiples of 3 and 2 multiples of 13 adding to a total of 12. So the probability is 12/30.
    Agree there

    limits660 Senior | Next Rank: 100 Posts
    Joined
    12 Jul 2006
    Posted:
    57 messages
    Followed by:
    2 members
    Post Wed Oct 25, 2006 4:23 am
    I believe its B

    _________________
    -
    Jeff Sacco
    www.jeffsacco.ca

    800guy Master | Next Rank: 500 Posts Default Avatar
    Joined
    27 Jun 2006
    Posted:
    354 messages
    Followed by:
    5 members
    Thanked:
    11 times
    Post Wed Oct 25, 2006 3:29 pm
    here's the OA:
    Total no from 1 to 30 = 30
    total no from 1 to 30 which r multiple of 3 = 10 (eg(3,6,9,12,15,18,21,24,27,30))
    total no from 1 to 30 which r multiple of 13 = 2 (eg 13,26)
    P(a or b ) = p(a) + p(b)
    p(a)= 10/30
    p(b)=2/30
    p(a) + p(b) = 10/30+2/30 = 2/5

    Best Conversation Starters

    1 Vincen 152 topics
    2 lheiannie07 61 topics
    3 Roland2rule 49 topics
    4 ardz24 40 topics
    5 LUANDATO 32 topics
    See More Top Beat The GMAT Members...

    Most Active Experts

    1 image description Brent@GMATPrepNow

    GMAT Prep Now Teacher

    141 posts
    2 image description EconomistGMATTutor

    The Economist GMAT Tutor

    107 posts
    3 image description GMATGuruNY

    The Princeton Review Teacher

    106 posts
    4 image description Rich.C@EMPOWERgma...

    EMPOWERgmat

    104 posts
    5 image description Matt@VeritasPrep

    Veritas Prep

    76 posts
    See More Top Beat The GMAT Experts