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Probability Function

  • 17-10-2013 01:09PM
    #1
    MacDanger
    Registered Users, Registered Users 2, Paid Member Posts: 3,881 ✭✭✭


    Hi All

    Have tried searching for the solution to this but can’t find what I’m looking for.

    I missed the lecture on this last week so that's half my problem!

    By specifying its probability function, p(X), find a random variable X with cumulative distribution function:

    Fx(t) = { 0, t < 3
    1/3, 3 ≤ t < 4
    1/2, 4 ≤ t < 5
    2/3, 5 ≤ t < 6
    1, t ≥ 6

    And calculate Pr (3 ≤ X ≤ 4)

    Any instruction on how to approach this would be much appreciated

    Thanks

    Neil


Comments

  • #2
    Yakuza
    Registered Users, Registered Users 2 Posts: 5,130 ✭✭✭Yakuza


    The probability function describes the discrete values and the probabilities they can take. The CDF as you describe above is the cumulative probability (i.e. the sum/integral of the probability functions up to the value you're looking at) of getting a value less than the value you're testing. For example, if F(5) = 0.5 and F(4) = 1/3 then the probability of getting a value between 4 and 5 is the difference between the two (1/6). Can you apply this to getting a value between 3 and 4?

    Some more info here: http://en.wikipedia.org/wiki/Cumulative_distribution_function


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