Results 1 to 4 of 4

Math Help - mutually exclusive events

  1. #1
    Senior Member sfspitfire23's Avatar
    Joined
    Oct 2009
    Posts
    273

    mutually exclusive events

    So, two mutually exclusive events A and B

    P(A or B)=P(A)+P(B).

    But what if the probabilities add up to be greater than 1? We can't subtract P(AandB).

    Can P(A or B) with mutually exclusive events be greater than 1?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,605
    Thanks
    1573
    Awards
    1
    Quote Originally Posted by sfspitfire23 View Post
    So, two mutually exclusive events A and B
    P(A or B)=P(A)+P(B).
    But what if the probabilities add up to be greater than 1? We can't subtract P(AandB).

    Can P(A or B) with mutually exclusive events be greater than 1?
    The answer is no. Not in the same probability space
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Senior Member sfspitfire23's Avatar
    Joined
    Oct 2009
    Posts
    273
    So, if P(A)=.9 and P(B)=.9 and the events are mutually exclusive, what is P(A or B)?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,605
    Thanks
    1573
    Awards
    1
    Quote Originally Posted by sfspitfire23 View Post
    So, if P(A)=.9 and P(B)=.9 and the events are mutually exclusive, what is P(A or B)?
    The point is the bit above is impossible. It cannot happen.
    Consider, P(A \cup B) = P(A) + P(B) - P(A \cap B) \leqslant 1.
    From the given P(A \cap B) \geqslant 0.8.
    Because P(A \cap B) \ne 0 the events are not mutually exclusive.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Mutually Exclusive Events
    Posted in the Advanced Statistics Forum
    Replies: 6
    Last Post: March 10th 2012, 02:20 PM
  2. Probability with mutually exclusive events
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: October 13th 2010, 07:06 PM
  3. Non-mutually/mutually exclusive events
    Posted in the Statistics Forum
    Replies: 1
    Last Post: September 29th 2010, 09:37 AM
  4. Mutually Exclusive Events
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: January 19th 2009, 07:10 PM
  5. Mutually exclusive events? need help for sure
    Posted in the Statistics Forum
    Replies: 4
    Last Post: August 8th 2006, 09:03 PM

Search Tags


/mathhelpforum @mathhelpforum