由0、1、2、3组成个位数字不是1的没有重复数字的四位数共有 个.
14
当千位数字为1时,;当千位数字不为1时,
所以共有6+8=14个
某次考试有70000名学生参加,为了了解这70000名考生的数学成绩,从中抽取1000名考生的数学成绩进行统计分析,在这个问题中,有以下四种说法:
(1)1000名考生是总体的一个样本;
(2)1000名考生数学成绩的平均数是总体平均数;
(3)70000名考生是总体;
(4)样本容量是1000.其中正确的说法有( )
A.1种
B.2种
C.3种
D.4种
用所给词的适当形式填空。
1. When the car (invent)?
2. I want to go somewhere (relax)
3. A stranger was seen (go) into the teacher's office by the girl.
4. Knocking into players and falling down would be . (danger)
5. The coat is used for (keep) water away.
6. (be) a volunteer is great.
7. I fix up bikes and give (they) away to children.
8. I love places where the people are really (friend)
9. I love singers (whom) write their own music.
10. Teenagers should (allow) to choose their own clothes.