一个袋子中有红、白、蓝三种颜色的球共24个，除颜色外其他特征完_爱下问搜题

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问题解答题

一个袋子中有红、白、蓝三种颜色的球共24个，除颜色外其他特征完全相同，已知蓝 * * 3个．若从袋子中随机取出1个球，取到红 * * 的概率是

1

6

．
（1）求红 * * 的个数；
（2）若将这三种颜色的球分别进行编号，并将1号红 * * ，1号白 * * ，2号蓝 * * 和3号蓝 * * 这四个球装入另一个袋子中，甲乙两人先后从这个袋子中各取一个球（甲先取，取出的球不放回），求甲取出的球的编号比乙大的概率．

答案

（1）设红 * * 有x个，

依题意得

x

24

=

1

6

，

解得x=4，

∴红 * * 有4个．

（2）由题意知本题是一个古典概型

试验发生包含的所有的基本事件有（红1，白1），（红1，蓝2），（红1，蓝3），（白1，红1），

（白1，蓝2），（白1，蓝3），（蓝2，红1），（蓝2，白1），（蓝2，蓝3），

（蓝3，红1），（蓝3，白1），（蓝3，蓝2），共有12个．

满足条件的事件包含的基本事件有（蓝2，红1），（蓝2，白1），（蓝3，红1），（蓝3，白1），

（蓝3，蓝2）共5个，

∴P（A）=

5

12

．

判断题

会计分录只能是一借一贷或一贷一借，不允许一借多贷或多借一贷。( )

阅读理解

In Britain today, is it possible to tell a person’s class just by looking at him? Physical details alone tell us about health, diet and the type of work a person does. A hundred years ago the working class often looked unhealthy, small and they were either too thin or too fat. The upper classes were often tall, sporting types who were used to a good diet and looked healthy. Today living and working conditions have improved, and such descriptions are no longer true. People are taller now than a hundred years ago. Everyone in Britain today is able to have free medicine, a good diet, acceptable working conditions and enough rest and leisure.

The clothes people choose to wear, however, do provide information about their backgrounds. Expensive clothes look expensive and show their wearer is rich. Clothes can provide other clues as well. The upper classes appear to be less interested in fashion and wear good quality clothes in non-bright colours, made of natural material like wool, leather and cotton. Lower working-class people often choose clothes in bright colours, made of man-made materials. A sociological explanation for this would be that colour and interest are missing from their lives, and therefore any opportunity to produce this is taken.

Clothes are available at a price within most people’s reach. New clothes make the wearer feel good and show some degree of wealth to the outside world. Today it is the younger people who spend most money on clothes. Fashion is no longer for the upper classes and the rich. Young people from all social classes spend a lot of money on clothes. Some new fashions are started by working—class people who want to look different and feel important. They want people to look at them.

1. In the past, a person’s appearance could not tell other people about his ________.

A. health B. diet C. occupation D. habits

2. The clothes people choose to wear tell us about their ________.

A. education B. richness C. backgrounds D. hobby

3. A working—class person may start a new fashion because ________.

A. she wants to draw the attention of other people

B. she wants to look different and healthy

C. she wants to show their wealth

D. she wants to show their taste

4. Which of the following statements is NOT true?

A. Expensive clothes look expensive and show the wearer is rich.

B. Working—class people prefer clothes in bright colours because they lack colour in their lives.

C. Today, it is still the upper class people who spend most money on clothes.

D. Today, fashion is no longer for the upper classes and the rich.