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Math Help - Probability HW Help Please.

  1. #1
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    Probability HW Help Please.

    Need help checking on my answers.

    The directions are "write the distribution for the formula and determine whether it is a probability distribution."

    The questions and my solutions are:

    1) P(X)=x/6 for X=1,2,3

    My solution is

    X = 1 2 3
    P(X) = 1/6 2/6 3/6-> 1/2

    Yes it is a probability distribution.

    2) P(X)=x for x =0.2, 0.3, 0.5

    My solution is

    X = 0.2 0.3 0.5
    P(X) = 0.2 0.3 0.5

    Yes it is a probability distribution.

    3) P(X)=X/6 for X = 3, 4, 7

    My solution is

    X = 3 4 7
    P(X) = 3/6 4/6 7/6

    No it is not a probability distribution.

    4) P(X)=X + 0.1 for X = 0.1, 0.02, 0.04

    My solution is

    X = 0.1 0.02 0.04
    P(X) = 0.2 0.12 0.14

    No it is not a probability distribution.

    5) P(X)=X/7 for X = 1, 2, 4

    My solution is

    X = 1 2 4
    P(X) = 1/7 2/7 4/7

    Yes it is a probability distribution.


    6) P(X)=X/(X+2) for X = 0, 1, 2

    My solution is

    X = 0 1 2
    P(X) = 0 1/3 2/4-> 1/2

    No it is not a probability distribution.



    Thanks. Can you guys tell me whether they are wrong and tell me what is wrong on my work. Thanks!
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  2. #2
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    Quote Originally Posted by Jimgotkp View Post
    Need help checking on my answers.

    The directions are "write the distribution for the formula and determine whether it is a probability distribution."

    The questions and my solutions are:

    1) P(X)=x/6 for X=1,2,3

    My solution is

    X = 1 2 3
    P(X) = 1/6 2/6 3/6-> 1/2

    Yes it is a probability distribution.

    2) P(X)=x for x =0.2, 0.3, 0.5

    My solution is

    X = 0.2 0.3 0.5
    P(X) = 0.2 0.3 0.5

    Yes it is a probability distribution.

    3) P(X)=X/6 for X = 3, 4, 7

    My solution is

    X = 3 4 7
    P(X) = 3/6 4/6 7/6

    No it is not a probability distribution.

    4) P(X)=X + 0.1 for X = 0.1, 0.02, 0.04

    My solution is

    X = 0.1 0.02 0.04
    P(X) = 0.2 0.12 0.14

    No it is not a probability distribution.

    5) P(X)=X/7 for X = 1, 2, 4

    My solution is

    X = 1 2 4
    P(X) = 1/7 2/7 4/7

    Yes it is a probability distribution.


    6) P(X)=X/(X+2) for X = 0, 1, 2

    My solution is

    X = 0 1 2
    P(X) = 0 1/3 2/4-> 1/2

    No it is not a probability distribution.



    Thanks. Can you guys tell me whether they are wrong and tell me what is wrong on my work. Thanks!
    All answers are correct. BUT ...... in each one I'd explicitly state that the 2 conditions for a pd are either met or not met.

    eg. 1) pd because the probabilities add up to 1 and all probabilties are greater than or equal to 0.

    eg. 6) Not a pd because the probabilities do NOT add up to 1.
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  3. #3
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    Joined
    May 2007
    Posts
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    alright. thanks very much!
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