Question

（6分）某初级中学准备随机选出七、八、九三个年级各1名学生担任领操员．现

已知这三个年级分别选送一男、一女共6名学生为备选人.

（1）请你利用树状图或表格列出所有可能的选法；

（2）求选出“两男一女”三名领操员的概率．

 

Answer 1

【答案】

（1）①300···························································································· 1分

②21≤x≤22··························································································· 3分

③12····································································································· 4分

（2）2800×=2240（人）······························································ 5分

 

答：该区所有学生中口语成绩为满分的人数约为2240人．··································· 6分

【解析】略