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stats - Probability Mass Function A probability mass...

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Probability Mass Function A probability mass function (PMF) has the form: P(X = x) = some expression (usually containing x) that produces a probability of observing x = P(x) 1. P(x) is between 0 and 1 (inclusive) for each x 2. ∑P(x) = 1 Mean of Discrete Random Variables The mean of a discrete random variable represents the average value of the random variable if you were to observe this variable over an indefinite period of time. The mean of a discrete random variable is written as µ µ = ∑xP(x) Variance of Discrete Random Variables The variance of a discrete random variable, X, is a parameter describing the variation of the corresponding population. The symbol used is σ 2 σ 2 = ∑(x - µ) 2 • P(x) σ 2 = ∑x 2 P(x) - µ 2 Using Binomial Table A.1 to Determine Probabilities The binomial PMFs have been tabulated in Table A.1 for various values of n and p. If n = 4 and p = 0.3 and you wish to find the P(2) locate n = 4 and x = 2.
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