Mean of a Random Variable

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Let X be a random variable whose possible values `x_1, x_2, x_3, ..., x_n` occur with probabilities `p_1, p_2, p_3,..., p_n`, respectively. The mean of X, denoted by µ, is the number `sum_(i=1)^n  x_i p_i` i.e. the mean of X is the weighted average of the possible values of X,  each value being weighted by its probability with which it occurs. 
The mean of a random variable X is also called the expectation of X, denoted by E(X).  
Thus , E(X) = µ  = `sum_(i = 1)^n x_ip_i = x_1p_1 + x_2p_2 + ... + x_np_n.`

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Probability part 26 (Mean of random variables) [00:12:30]
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