InterviewSolution
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InterviewSolution
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If the standard deviation of the random variable X is `sqrt(3pq)` and mean is 3p then `E(x^(2))`= . . .A. `3pq + 3q^(2)`B. `3p(1+2p)`C. `3pq + 3p^(2)`D. `3p(1+2p)` |
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Answer» Correct Answer - B We have standard deviaiton of `X = sqrt(3pq)` `rArr Var (X) = 3pq` and mean `E(X) = 3p` Now `3qp = E(x^(2)) - (3p^(2)) " "(because Var (x) = E(X^(2)) - (E(X)^(2)))` `rArr " "E(X^(2)) = 3pq + 9p^(2)` ` = 3p (1-p) + 9p^(2)" "(because p + q=1)` `= 3p - 3p^(2) + 9p^(2)` `rArr 3p + 6p^(2) rArr 3p(1+2p)` |
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