某单位有技工18人,技术员12人,工程师6人,现从这些人中抽取一个容量为n的样本.如果采用系统抽样和分层抽样的方法抽取,则都不用剔除个体;如果容量增加1个,则在采用系统抽样时,需在总体中剔除1人,由此推断样本容量n为_______.
6
总体中的个体数为18+12+6=36,由题意n整除36,且n+1整除35,∴n=4或6.
又∵也可采用分层抽样,而三种人员之比是18∶12∶6=3∶2∶1,
∴6整除n,即n=6.
| 完形填空。 | ||||
| "Imagine you are walking along the road. Suddenly you fall over and all the passers-by burst into laughter. You feel very 1 and think the world is laughing at you . But in fact, five minutes later, they have 2 it ever happened." The other day when I came across these words in an article, I didn't agree with the 3 . The author thinks the best thing to do in this kind of 4 is to pretend nothing has happened, and so avoid 5 trouble. I admit that we should keep 6 because "Your tears will only remind others of what happened, while your 7 can let them forget it." But this is far from satisfactory. We should do 8 to make things better. I used to be a(n) 9 girl and not very good at maths. Our new maths teacher asked me a question and I still remember how I hung my head in 10 when I couldn't answer it. "If you don't know the answer, just tell me." the teacher said, "If you don't how can I know 11 you know the answer or not?" All of my classmates burst into laughter. My face turned red but the teacher 12 me to go to the blackboard and 13 what I knew. If I had 14 the words in the article, I would have given up. But I tried my best. And to everyone's 15 , I succeeded! The teacher smiled and said, "Well done! I 16 you could do it!" Since then, I have become active in maths as 17 as in other subjects. I used to think doing maths exercises was a waste of time. But now, I know 18 I do can make things better. Everyone is the 19 of his own fate. If we make mistakes, we should take on an active 20 . Laugh, and the world laughs with you; weep (哭泣), and you weep alone. | ||||
|