(Ⅰ)由题意知本题是一个古典概型, 设样本中两名男生分别为a,b,5名女生分别为c,d,e,f,g,则基本事件空间为; (abc)(abd)(abe)(abf)(abg)(acd)(ace)(acf)(acg)(ade)(adf)(adg) (aef)(aeg)(afg)(bcd)(bce)(bcf)(bcg)(bde)(bdf)(bdg)(bef)(beg) (bfg)(cde)(cdf)(cdg)(cef)(ceg)(cfg)(def)(deg)(dfg)(efg)共35种, 其中既有男又有女的事件为前25种, 故P(“抽出的3人中既有男生也有女生”)==. (Ⅱ)k==4.43>3.84, 对照参考表格,结合考虑样本是采取分层抽样抽出的,可知有95%以上的把握认为学生选报文理科与性别有关. |