设随机变量X与-X服从同一均匀分布U[a，b]，已知X的概率密度f(x)_爱下问搜题

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问题填空题

设随机变量X与-X服从同一均匀分布U[a，b]，已知X的概率密度f(x)的平方f²(x)也是概率密度，则b=______．

答案

参考答案：[*]

解析：

[分析]：如果X～U[a，b]，则-X～U[-b，-a]，现X与-X同分布，故有a=-b，即X～U[-b，b)]．
这时，[*]
f²(x)也是概率密度，有
[*]

单项选择题

更年期的特点中下述何项是正确的( )

A．更年期一般是在55岁以上
B．更年期是恶性肿瘤的好发时期
C．更年期就是绝经期
D．更年期是无排卵性功血的好发时期
E．更年期卵巢中卵泡已耗尽

填空题

选词填空。

name, develop, divide, bear, keep, practice, include, invent

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7. It _____ you healthy.