问题 填空题

从自动打包机包装的食盐中,随机抽取20袋,测得各袋的质量分别为(单位:g):

492  496  494  495  498  497  501  502  504  496

497  503  506  508  507  492  496  500  501  499

根据频率分布估计总体分布的原理,该自动包装机包装的袋装食盐质量在497.5g~501.5g之间的概率约为______.

答案

由已知中抽取20袋,各袋的质量为(单位:g):

492  496  494  495  498  497  501  502  504  496

497  503  506  508  507  492  496  500  501  499

其中食盐质量在497.5g~501.5g之间有

498   501  500  501  499共5袋

故自动包装机包装的袋装食盐质量在497.5g~501.5g之间的概率P=

5
20
=
1
4

故答案为:

1
4

单项选择题
完形填空

Brazil has become one of the developing world’s great successes at reducing population growth but more by accident than design. While countries such as India have made joint efforts to reduce birth rates, Brazil has had better result without really trying, says George Martine at Harvard.

Brazil’s population growth rate has dropped from 2.99% a year between 1951 and 1960 to 1.93% a year between 1981 to 1990, and Brazilian women now have only 2.7 children on average. Martine says this figure may have fallen still further since 1990, an achievement that makes it the envy of many other Third World countries.

Martine puts it down to, among other things, soap operas and installment plans introduced in the 1970s. Both played an important, although in direct, role in lowering the birth rate. Brazil is one of the world’s biggest producers of soap operas. Globo, Brazil’s most popular television network, shows three hours of soaps six nights a week, while three others show at least one hour a night. Most soaps are based on wealthy characters living the high life in big cities.

“ Although they have never really tried to work in a message towards the problems of reproduction, they describe middle and upper class values ---- not many children, different attitudes towards sex, women working,” says Martine. “ They sent this image to all parts of brazil and made people conscious of behavior and other values, which were put into a very attractive package.”

Meanwhile, the installment plans tried to encourage the poor to become consumers. “ This led to an enormous change in consumption patterns and consumption was incompatible with unlimited reproduction.” says Martine.

小题1:According to the passage, the two factors that lead to the success of population control in Brazil are _______________________________________.

小题2:The underlined phrase “ put down to ” in paragraph 3 has the closest meaning to _________________________________.

小题3:What made Brazil the envy of many other Third World countries?

_________________________________________________________________

小题4:Why did the author say that soap operas helped in lowering the birth rate?

_________________________________________________________________