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Question
The p.m.f. of a random variable X is
`"P"(x) = 1/5` , for x = I, 2, 3, 4, 5
= 0 , otherwise.
Find E(X).
Solution
E(X) = `sum_(i = 1)^5 x."P"(x)`
= `1 xx 1/5 + 2 xx 1/5 xx 3 xx 1/5 + 4 xx 1/5 + 5 xx 1/5`
= `15/5`
= 3
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