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问题 解答题

某商场在节日期间搞有奖促销活动，凡购买一定数额的商品，就可以摇奖一次．摇奖办法是在摇奖机中装有大小、质地完全一样且分别标有数字1～9的九个小球，一次摇奖将摇出三个小球，规定：摇出三个小球号码是“三连号”（如1、2、3）的获一等奖，奖1000元购物券；若三个小球号码“均是奇数或均是偶数”的获二等奖，奖500元购物券；若三个小球号码中有一个是“8”的获三等奖，奖200元购物券；其他情形则获参与奖，奖50元购物券．所有获奖等第均以最高奖项兑现，且不重复兑奖．记X表示一次摇奖获得的购物券金额．

（1）求摇奖一次获得一等奖的概率；

（2）求X的概率分布列和数学期望．

答案

（1）记“摇奖一次获得一等奖”为事件A，

连号的可能情况有：123，234，345，456，567，678，789共7种情况．

∴P（A）=

7
C39
=
7
84
=
1
12
．

故摇奖一次获得一等奖的概率为

1
12
．

（2）由题设知X的可能取值分别为1000，500，200，50．

P（X=1000）=

1
12
，P（X=500）=
C35
+
C34
84
=
1
6
，

P（X=200）=

C25
+
C15
C13
-2
84
=
23
84
，

P（X=50）=

C25
+
C15
C13
-5
84
=
40
84
=
10
21
，

∴X的分布列如下：

 X 1000 500 200 50
 P 
1
12
 
1
6
 
23
84
 
10
21
EX=
1
12
×1000+
1
6
×500+
23
84
×200+
10
21
×50=
5150
21
．

单项选择题 共用题干题

公众的药品安全需求日益增长，发达国家在现代化、城市化、工业化长期进程中分阶段出现的安全风险在我国现阶段集中出现，我们正处于药品安全风险高发期。药品风险组成分2部分：天然风险和人为风险。

不属于人为风险的是（）

A.药品未知的不良反应

B.不合理用药

C.药品质量问题

D.用药差错

E.认知局限
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单项选择题

At some time in your life you may have a p desire to do something strange or terrible. However, chances are that you don’t act on your impulse, but let it pass instead. You know that to commit the action is wrong in some way and that other people will not accept your behavior.
Perhaps the most interesting thing about the phenomenon of the behavior is how it can change over the years within the same society, how certain behavior and attitudes once considered taboo can become perfectly acceptable and natural at another point in time. Topics such as death, for example, were once considered so upsetting and unpleasant that it was a taboo to even tall about them. Now with the publication of important books such as "On Death and Dying" and "Learning to Say Goodbye", people have become more aware of the importance of expressing feelings about death and, as a result, are more willing to talk about this taboo subject.
One of the newest taboos in American society is the topic of fat. Unlike many other taboos, fat is a topic that Americans tall about constantly. It’s not taboo to tall about fat; it’s taboo to be fat. The "thin" look is thin, not fat.
In the work world, most companies prefer youthful-looking, trim executives to sell their image as well as their products to the public. The thin look is associated with youth, vigor and success. The fat person, on the other hand, is thought of as lazy and lacking in energy, self- respect. After all, people think, how can people who care about themselves, and therefore the way they look, permit themselves to become fat In an image-conscious society like the U.S., thin is "in", fat is "out".

According to the passage, we can infer that taboo is ______.

A. a crime committed on impulse
B. an unfavorable impression left on other people
C. a behavior considered unacceptable by the public
D. a p desire to do something strange or terrible
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