设随机变量<imgwidth="100"height="25"v:shapes="_x0000_i1119"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb09.files/image157.png">独立同分布,且<imgwidth="223"height="41"v:shapes="_x0000_i1120"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb09.files/image159.png">,则<imgwidth="115"height="46"v:shapes="_x0000_i1121"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb09.files/image161.png">()
①
<imgwidth="37"height="21"v:shapes="_x0000_i1122"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb09.files/image163.png">
②
<imgwidth="36"height="21"v:shapes="_x0000_i1123"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb09.files/image165.png">
③
<imgwidth="16"height="41"v:shapes="_x0000_i1124"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb09.files/image130.png">