The variance of a random variable measures how far from the expected value its values typically are.
随机变量的方差衡量随机变量值与期望值偏离的程度。
The technical definition of variance is the random variable's second central moment, the weighted average of the square of the differences from the expected value.
3方差的专业定义是随机变量的二次中心矩，与期望值之差的平方的加权平均值。
On the other hand, the moment, the second moment and variance of the present value random variables about some life annuities and annuities with random interest rate are gotten.
另一方面讨论了随机利率下的一些离散年金、连续年金和连续生存年金现值随机变量的一阶和二阶原点矩及其方差。
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