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Question
Define Mathematical expectation in terms of discrete random variable
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Solution
Let X be a discrete random variable with probability mass function (p.m.f) P(x).
Then, its expected value is defined by E(X) = `sum_x x"p"(x)`
In other words,
If x1, x2, x3,…… xn are the different values of X, and p(x1), p(x2) …..p(xn) are the corresponding probabilities, then E(X) = x1 p(x1) + x2 p(x2) + x3 p(x3) +… xn p(xn)
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