<p>设随机变量<img src="https://learnfile.20230611.cn/learnAppQuestion/3e/5c/3e5c1b5346ff82cfb247ed0b5657cd62.jpg" style="width: 100%;height: auto;">，令<img src="https://learnfile.20230611.cn/learnAppQuestion/7e/96/7e96155b42ce53c637572727f84b0805.jpg" styl