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

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist 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
  • 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
  • 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
  • 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
  • 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

OG-17

This topic has 4 expert replies and 0 member replies
Joy Shaha Senior | Next Rank: 100 Posts Default Avatar
Joined
05 May 2016
Posted:
59 messages
Thanked:
3 times

OG-17

Post Sat Nov 19, 2016 1:14 pm
Elapsed Time: 00:00
  • Lap #[LAPCOUNT] ([LAPTIME])
    The probability that event M will not occur is 0.8 and the probability that
    event R will not occur is 0.6. If events M and R cannot both occur, which of
    the following is the probability that either event M or event R will occur?
    A) 1/5 B) 2/5 C) 3/5 D) 4/5 E) 12/25

    Need free GMAT or MBA advice from an expert? Register for Beat The GMAT now and post your question in these forums!
    Post Sat Nov 19, 2016 2:48 pm
    Joy Shaha wrote:
    The probability that event M will not occur is 0.8 and the probability that
    event R will not occur is 0.6. If events M and R cannot both occur, which of
    the following is the probability that either event M or event R will occur?
    A) 1/5 B) 2/5 C) 3/5 D) 4/5 E) 12/25
    If the probability that M will not occur is .8, the probability that it will occur is .2.

    If the probability that R will not occur is .6, the probability that it will occur is .4.

    So P(M) = .2 and P(R) = .4.

    P(M or R) = P(M) + P(R) - P(M and R).

    Because we're told that P(M and R) = 0, we have

    P(M or R) = .2 + .4 = .6 = 3/5.

    The answer is C

    _________________
    Veritas Prep | GMAT Instructor

    Veritas Prep Reviews
    Save $100 off any live Veritas Prep GMAT Course

    Enroll in a Veritas Prep GMAT class completely for FREE. Wondering if a GMAT course is right for you? Attend the first class session of an actual GMAT course, either in-person or live online, and see for yourself why so many students choose to work with Veritas Prep. Find a class now!

    GMAT/MBA Expert

    Post Fri Nov 25, 2016 3:22 pm
    It might be easier to see this using less abstract terms.

    Suppose I told you that the Mariners have a 20% chance of winning the World Series, and that the Rangers have a 40% chance of winning the World Series. Since at most one of these teams could win, the probability that the Mariners OR the Rangers win = 20% + 40% = 60%.

    Enroll in a Veritas Prep GMAT class completely for FREE. Wondering if a GMAT course is right for you? Attend the first class session of an actual GMAT course, either in-person or live online, and see for yourself why so many students choose to work with Veritas Prep. Find a class now!
    Post Sun Nov 27, 2016 5:51 pm
    Joy Shaha wrote:
    The probability that event M will not occur is 0.8 and the probability that
    event R will not occur is 0.6. If events M and R cannot both occur, which of
    the following is the probability that either event M or event R will occur?
    A) 1/5 B) 2/5 C) 3/5 D) 4/5 E) 12/25
    We are given that the probability that event M will not occur is 0.8 and the probability that event R will not occur is 0.6, and that events M and R cannot both occur.

    We need to determine the probability that either event M or event R will occur.

    The probability that event M will occur is 1 - 0.8 = 0.2 = 1/5

    The probability that event R will occur is 1 - 0.6 = 0.4 = 2/5

    Recall that the formula for the probability of event A or event B occurring is P(A or B) = P(A) + P(B) - P(A and B); therefore:

    P(M or R) = P(M) + P(R) - P(M and R).

    Since we are told that events M and R cannot both occur, that means P(M and R) = 0 and thus the probability that either event M or event R will occur is:

    P(M or R) = 1/5 + 2/5 - 0 = 3/5.

    Answer:C

    _________________

    Scott Woodbury Stewart Founder & CEO
    GMAT Quant Self-Study Course - 500+ lessons 3000+ practice problems 800+ HD solutions
    5-Day Free Trial 5-DAY FREE, FULL-ACCESS TRIAL TTP QUANT

    Post Sun Dec 11, 2016 11:33 pm
    Joy Shaha wrote:
    The probability that event M will not occur is 0.8 and the probability that
    event R will not occur is 0.6. If events M and R cannot both occur, which of
    the following is the probability that either event M or event R will occur?
    A) 1/5 B) 2/5 C) 3/5 D) 4/5 E) 12/25
    Hi Joy,

    Given that:

    Probability of event M NOT to occur = P(M') = 0.8
    => Probability of event M to occur = P(M) = 1 - 0.8 = 0.2

    Probability of event R NOT to occur = P(R') = 0.6
    => Probability of event R to occur = P(R) = 1 - 0.6 = 0.4

    We are given that either of the two events can occur, thus,

    (Probability of M to occur * Probability of R NOT to occur) + (Probability of M NOT to occur * Probability of R to occur)
    = P(M)*P(R') + P(M')*P(R) = 0.2*0.6 + 0.8*0.4 = 0.12 + 0.48 = 0.60 = 3/5.

    Hope this helps!

    -Jay

    _________________
    Manhattan Review GMAT Prep

    Locations: New York | Mumbai | Ho Chi Minh City | Budapest | and many more...

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

    Best Conversation Starters

    1 Vincen 180 topics
    2 lheiannie07 61 topics
    3 Roland2rule 61 topics
    4 ardz24 40 topics
    5 VJesus12 14 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 Rich.C@EMPOWERgma...

    EMPOWERgmat

    102 posts
    3 image description GMATGuruNY

    The Princeton Review Teacher

    99 posts
    4 image description Jay@ManhattanReview

    Manhattan Review

    86 posts
    5 image description Matt@VeritasPrep

    Veritas Prep

    80 posts
    See More Top Beat The GMAT Experts