(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.
(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
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(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.(1)请你利用树状图或表格列出所有可能的选法;
2.(2)求选出“两男一女”三名领操员的概率.
查看答案和解析>>
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(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.(1)请你利用树状图或表格列出所有可能的选法;
2.(2)求选出“两男一女”三名领操员的概率.
查看答案和解析>>
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