若随机变量X的方差D(X)存在,则P{∣X-E(X)∣/a﹥1}≤()

若随机变量X的方差D(X)存在,则P{∣X-E(X)∣/a﹥1}≤()

A.D(X)

B.1

C.D(X)/a2

D.a2D(X)

正确答案是C

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