Sponsored Ad:
Page 1 of 2 12 LastLast
Results 1 to 10 of 11

Thread: Probability-neither A nor B

  1. #1
    An Urch Guru Pundit Swami Sage Da_Gr8_Mperor's Avatar
    Join Date
    Mar 2006
    Posts
    750
    Rep Power
    12


    Good post? Yes | No

    Probability-neither A nor B

    Sponsored Ad:
    The probability that event A will happen is 0.5 and the event B will happen is 0.4. What is the range of the probability that neither A nor B will happen?


    0.5
    0.6
    0.1
    0.9
    0.2
    Last edited by Da_Gr8_Mperor; 05-13-2006 at 06:55 PM. Reason: Automerged post

  2. #2
    Eager! Cloudnineast's Avatar
    Join Date
    May 2006
    Posts
    50
    Rep Power
    9


    Good post? Yes | No
    Is it .1?
    SPOILER: Life is what happens to you while you are making other plans

  3. #3
    An Urch Guru Pundit Swami Sage Da_Gr8_Mperor's Avatar
    Join Date
    Mar 2006
    Posts
    750
    Rep Power
    12


    Good post? Yes | No
    Nopes,cloud

  4. #4
    An Urch Guru Pundit Swami Sage
    Join Date
    May 2004
    Posts
    1,234
    Rep Power
    15


    Good post? Yes | No
    Range = max prob - min prob.

    P(A or B) >= P(A)
    P(A or B) >= P(B)

    Editing..am still debating how to approach this pblm
    0.5 <= P(A or B) <= 0.9
    Range of P(A or B) = 0.4

    I guess, my initial approach was in line with sdasar's explanation below:

    maximize P(A or B)
    P(A or B) = P(A) + P(B) - P(A&B)
    for max prob => P(A&B) = 0 ( A and B are mutually exclusive)
    => 0.9
    neither = 0.1

    minimize p(A or B) = p(A) + p(B) - P(A&B)
    p(A&B) = p(A)*P(B) for independent events
    = 0.5*0.4 = 0.2
    p(A or B) = 0.7
    neither = 0.3

    Range = 0.3-0.1 = 0.2
    Last edited by GMAT-HELP; 05-13-2006 at 09:05 PM.

  5. #5
    Within my grasp!
    Join Date
    Apr 2005
    Posts
    180
    Rep Power
    10


    Good post? Yes | No
    interesting,this the fisrt time I come across such a question!
    Thanks guys!

  6. #6
    An Urch Guru Pundit Swami Sage
    Join Date
    Mar 2006
    Posts
    559
    Rep Power
    11


    Good post? Yes | No
    The other way of doing is

    When A & b are mutually independent events:

    The probability that A won't happen is 0.5
    The probability that B won't happen is 0.6

    Probability that both events (neither A nor B) happen is 0.3

    When A & B are mutually dependent(exclusive) events:

    The probbality that either A or either B happen is 0.9 and none of them happen is 0.1

    The range is 0.2

  7. #7
    An Urch Guru Pundit Swami Sage
    Join Date
    May 2004
    Posts
    1,234
    Rep Power
    15


    Good post? Yes | No
    Sdasar,
    I got the same ans as you did but I was wondering what happens in the scenario where B is a subset of A, then P(A or B) would be 0.5? and neither A nor B would be 0.5 too?

    Thanks,
    GMAT-HELP

  8. #8
    An Urch Guru Pundit Swami Sage
    Join Date
    Mar 2006
    Posts
    559
    Rep Power
    11


    Good post? Yes | No
    GMAT-HELP,

    0.3 and 0.1 refers to well defined populations. One probablity refers to truly independent random events and the other to truly mutually exclusive events.

    If there is any bias between events A and B as you eluded, all bets are off. I don't think the problem (based on the answers) is implying anything other than the above scenarios.

    Thanks,
    sdasar

  9. #9
    An Urch Guru Pundit Swami Sage
    Join Date
    Mar 2006
    Posts
    716
    Rep Power
    11


    Good post? Yes | No
    Quote Originally Posted by sdasar
    The other way of doing is

    When A & b are mutually independent events:

    The probability that A won't happen is 0.5
    The probability that B won't happen is 0.6

    Probability that both events (neither A nor B) happen is 0.3

    When A & B are mutually dependent(exclusive) events:

    The probbality that either A or either B happen is 0.9 and none of them happen is 0.1

    The range is 0.2
    Sdasar: how do you get P(both events won't happen) = 0.3?

    Gmathelp: like your 2nd explanation. thanks
    Last edited by jjaacc; 05-14-2006 at 05:59 AM. Reason: Automerged post

  10. #10
    An Urch Guru Pundit Swami Sage
    Join Date
    May 2004
    Posts
    1,234
    Rep Power
    15


    Good post? Yes | No
    Quote Originally Posted by jjaacc
    Sdasar: how do you get P(both events won't happen) = 0.3?

    Gmathelp: like your 2nd explanation. thanks
    P(both events won't happen) = p(A won't happen)*p(B won't happen)
    = 0.6*0.5 = 0.3

Page 1 of 2 12 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. probability
    By astral glow in forum GRE Math
    Replies: 16
    Last Post: 06-21-2012, 03:09 PM
  2. probability
    By mbawannabe in forum GMAT Problem Solving
    Replies: 2
    Last Post: 04-30-2008, 09:33 PM
  3. Probability
    By kluevehe in forum GMAT Problem Solving
    Replies: 1
    Last Post: 04-28-2008, 07:14 AM
  4. Probability
    By grems in forum GMAT Problem Solving
    Replies: 2
    Last Post: 04-26-2008, 06:51 PM
  5. Probability
    By dahiya in forum GMAT Math
    Replies: 2
    Last Post: 06-15-2005, 07:17 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

SEO by vBSEO ©2010, Crawlability, Inc.