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Thread: Identifying n, X, p, and q Please Help

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    Identifying n, X, p, and q Please Help




    I want to see if I'm identifying these properties correctly, or am I wrong:

    n=4 X=.2 p=.0016 q=.9984

    Here's the problem:

    Instructor gives a quiz of 4 questions, each with 5 possible answers. Only one answer is correct. Identify the values of n, X, p, and q

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    Re: Identifying n, X, p, and q Please Help

    I guess you need to figure out something about the Binomial distribution. Therefore you should have

    - n as the number of trials (questions)
    - p as the probability of success (randomly guessing correctly)
    - q = 1 - p

    and the last thing X, in the probability notation the uppercase letter usually representing a random variable. So in this case it may just mean a Binomial random variable (which should be representing the number of questions guessed correctly). But if you want to represent the realized value of this random variable, then usually we will use the lowercase (which is the actual number of questions guessed correctly).

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    Tracy (03-22-2013)

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    Re: Identifying n, X, p, and q Please Help


    Thanks BGM!

    This is what I ended up with...

    n=4 X=0,1,2,3,4 p=.20 q=.80

    The question goes on to ask:
    What is the probability of scoring a 75% or higher on the quiz?

    I came up with the following:

    .20 x .20 x .20= .008

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