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问题 问答题

某批发市场对某种商品的周销售量(单位:吨)进行统计，最近100周的统计结果如下表所示：　　周销售量234频数205030（1）根据上面统计结果,求周销售量分别为2吨，3吨和4吨的频率；　　（2）已知该商品每吨的销售利润为2千元，ξ表示该种商品两周销售利润的和(单位：千元)，若以上述频率作为概率，且各周的销售量相互独立，求ξ的分布列和数学期望。

答案

参考答案：解：（1）周销售量为2吨，3吨和4吨的频率分别为0.2，0.5和0.3。　　（2）ξ的可能值为8，10，12，14，16，且　　P（ξ=8）=0.22=0.04，　　P（ξ=10）=2×0.2×0.5=0.2，　　P（ξ=12）=0.52+2×0.2×0.3=0.37，　　P（ξ=14）=2×0.5×0.3=0.3，　　P（ξ=16）=0.32=0.09。　　ξ的分布列为　　ξ810121416P0.040.20.370.30.09Eξ=8×0.04+10×0.2+12×0.37+14×0.3+16×0.09=12.4（千元）。

阅读理解

Fifty-three years ago Barbie Millicent Roberts first appeared in the world of toys.

Since then, Barbie doll, as everyone called her,has become the most successful toy doll in history. Her parent,the Mattel Company,said that 90% of all Ame”rican girls between 3 and 10 have at least one Barbie at home.

However, Barbie is facing some trouble at present (现在). There are many similar dolls on the market in competiotion with her. Another doll named Bratz, for example, come to life thirteen years ago. She looked more like today’s pop stars with heavy makeup(浓妆) and miniskirts. And her company offers more kind of clothes too.

It seems that Barbie has lost her magic among older girls. “ For younger girls, playing with a Barbie is much fun. But when you get older, you want something smarter and more modern,” says Vera Shepherd, a shop assitant in a New York toy store.

It is good news that on the international market. Barbie is still No. 1. although Mttel is selling ferwer Barbies int the United States three years, sales in other countries are still going up.in January 2009, Mattel openee its first Barbie store in Shanghai, where girls can shop, eat, drink or even become fashion designers for their own Barbies.

Mattel is planning big celebration for Barbie’s 53rd birthday. Fashion designers from all over the world have been called to make new dresses for Barbie. How long will Barbie stay popuplar in the world of toy dolls? It is hard to say, but 小题1:is surely not the age to retire(退休)。

61. Barbie’s family name is______.

A．Roberts

B．millicent

C．Shepherd

D．Bratz小题2:Barbie’s trouble is that__________.

A．it wears heavy makeup and miniskirts.

B．other dolls are more popular with little girls.

C．other dolls are trying to beat her in the market.

D．it has become less popular in the international market.小题3:Girls can do the following in the first Barbie shop in Shanghai except_______.

A．going shopping

B．having food

C．drinking juice

D．taking photos小题4:What’s the meaning of the underline words “fashion designers” in the passage?

A．珠宝设计师

B．发型设计师

C．舞台设计师

D．服装设计师小题5:What is the best title of the passage?

A．First Barbie Shop in Shanghai

B．Barbie’s Past and present

C．Barbie’s 53rd Birthday Party

D．Barbie Lost Her Magic
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单项选择题

对同一种商品采用不同级别的包装，以适应不同的购买力水平，这种包装决策叫做（）。

A.差异包装决策

B.复用包装决策

C.改变包装决策

D.分等级包装决策
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