21. Let X be a strictly positive random variable, whose expectation equals to 0.5 and variance equals to 1. Which of the following statement is the most correct one? (A)Ein(2X)]＞0.5；(B)Elin(2X)]sO；(C)In(E[X])＞-0.2；(D)In(E[X2])＜-0.3；(E)2n(E[X])>-1.

2. A 95% confidence interval of a population mean is . Which of the following statement is the most correct one? (A) If random samples were drawn again and again, with computed each time, the population mean would lie in the interval 95% of the samples. (B)If = 0.5, the population mean would lie in the interval [0.1,0.5] with 95% probability. (C) If = 0.55, the population mean might still lie outside the interval [0.05,0.55)(D) If= 0.56, the population mean would ie in the interval [0.03, 0.56] greater than 95% probability. (E) a and c.

21. Let X be a strictly positive random variable, whose expectation equals to 0.5 and variance equals to 1. Which of the following statement is the most correct one?
(A)Ein(2X)]＞0.5；
(B)Elin(2X)]sO；
(C)In(E[X])＞-0.2；
(D)In(E[X²])＜-0.3；
(E)2n(E[X])>-1.

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