Results 1 to 5 of 5

Math Help - probability distribution

  1. #1
    Junior Member
    Joined
    Dec 2007
    Posts
    25

    probability distribution

    When the health department tested private wells in a county for two impurities commonly found in drinking water, it found that 20% of the wells had neither impurity, 40% had impurity A, and 50% had impurity B. (Obviously, some had both.) If a well is randomly chosen from those in the county, find the probability distribution for Y, the number of impurities found in the well.

    I know y = 0 is 20%.

    But how is y = 1 70% and y = 2 10%?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,648
    Thanks
    1596
    Awards
    1
    Quote Originally Posted by Chizum View Post
    When the health department tested private wells in a county for two impurities commonly found in drinking water, it found that 20% of the wells had neither impurity, 40% had impurity A, and 50% had impurity B. (Obviously, some had both.) If a well is randomly chosen from those in the county, find the probability distribution for Y, the number of impurities found in the well.
    I know y = 0 is 20%.
    But how is y = 1 70% and y = 2 10%?
    See the Venn diagram.
    Y=1 means exactly one. A and not B or B and not A: .3+.4=.7
    Y=2 means both A & B: .1
    Attached Thumbnails Attached Thumbnails probability distribution-venn2.gif  
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Dec 2007
    Posts
    25
    Do you find A & B by .7 + .2 + ? = 1?

    Or do you calculate it somehow? It seems like, to calculate it, A and B would have to be dependent and you'd have to find P(B|A).
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,648
    Thanks
    1596
    Awards
    1
    Quote Originally Posted by Chizum View Post
    Do you find A & B by .7 + .2 + ? = 1?
    Or do you calculate it somehow? It seems like, to calculate it, A and B would have to be dependent and you'd have to find P(B|A).
    I think that you need a sit-down (face to face) session with your instructor.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Junior Member
    Joined
    Dec 2007
    Posts
    25
    Quote Originally Posted by Plato View Post
    I think that you need a sit-down (face to face) session with your instructor.
    Granted, but let me ask:

    Is it possible to find P(A and B) without having first found the individual probabilities of A and B (A = 30% and B = 40%)?

    I just want a yes or no. Then I'll leave.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 1
    Last Post: February 18th 2010, 01:54 AM
  2. Probability distribution
    Posted in the Advanced Statistics Forum
    Replies: 0
    Last Post: November 29th 2008, 06:59 AM
  3. probability distribution
    Posted in the Advanced Statistics Forum
    Replies: 2
    Last Post: November 16th 2007, 04:34 AM
  4. probability distribution of X
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: May 18th 2006, 12:22 PM
  5. Probability Distribution
    Posted in the Advanced Statistics Forum
    Replies: 3
    Last Post: April 26th 2006, 06:44 PM

Search Tags


/mathhelpforum @mathhelpforum