2015 高考数学第 4 题答案解析

A. $P\left(Y \geq \mu_{2}\right) \geq P\left(Y \geq \mu_{1}\right)$

B. $P\left(X \leq \sigma_{2}\right) \leq P\left(X \leq \sigma_{1}\right)$

C. 对任意正数 $t, P(X \leq t) \geq P(Y \leq t)$

D. 对任意正数 $t, P(X \geq t) \geq P(Y \geq t)$