设<imgwidth="12"height="14"v:shapes="_x0000_i1185"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image253.png">个随机变量<imgwidth="86"height="22"v:shapes="_x0000_i1186"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image239.png">是独立同分布,<imgwidth="164"height="42"v:shapes="_x0000_i1187"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image255.png"><imgwidth="32"height="20"v:shapes="_x0000_i1188"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image257.png"><imgwidth="115"height="42"v:shapes="_x0000_i1189"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image259.png">,则下列结论中,正确的是()
①
<imgwidth="12"height="14"v:shapes="_x0000_i1190"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image261.png">是<imgwidth="12"height="12"v:shapes="_x0000_i1191"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image263.png">的无偏估计量
②
<imgwidth="12"height="14"v:shapes="_x0000_i1192"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image261.png">是<imgwidth="12"height="12"v:shapes="_x0000_i1193"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image263.png">的极大似然估计量
③
<imgwidth="12"height="14"v:shapes="_x0000_i1194"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image261.png">是<imgwidth="12"height="12"v:shapes="_x0000_i1195"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image263.png">的极大似然估计量
④
<imgwidth="12"height="14"v:shapes="_x0000_i1196"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image261.png">是<imgwidth="12"height="12"v:shapes="_x0000_i1197"src="http://wljy.whut.edu.cn:80/uploadfiles/word/xxdsb11.files/image263.png">的极大似然估计量