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Question
How do you defi ne variance in terms of Mathematical expectation?
Solution
The variance of X is defined by
Var(X) = `sum[x - "E"("x")]^2 "p"(x)`
If X is discrete random variable with probability mass function p(x).
Var(X) = `int_-oo^oo [x - "E"("X")]^2 "f"_x (x) "d"x`
If X is continuous random variable with probability density function fx (x).
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