随机变量<imgwidth="19"height="17"v:shapes="_x0000_i1095"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb08.files/image127.png">服从正态分布<imgwidth="50"height="21"v:shapes="_x0000_i1096"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb08.files/image129.png">,则<imgwidth="75"height="21"v:shapes="_x0000_i1097"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb08.files/image131.png">()
①
<imgwidth="98"height="49"v:shapes="_x0000_i1098"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb08.files/image133.png">
②
<imgwidth="64"height="44"v:shapes="_x0000_i1099"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb08.files/image135.png">
③
<imgwidth="90"height="49"v:shapes="_x0000_i1100"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb08.files/image137.png">
④
<imgwidth="90"height="49"v:shapes="_x0000_i1101"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb08.files/image139.png">