问题 解答题

某服务厂生产一种西装和领带,西装每套定价200元,领带每条定价40元.厂方在开展促销活动期间,向客户提供两种优惠方案:(I)买一套西装送一条领带;

(II)西装和领带均按定价的90%付款.某超市经理现要到该服务厂购买西装20套,领带若干条(不少于20条).

(1)设购买领带为x(条),采用方案I购买时付款数为y1(元),采用方案II购买时付款数为yn(元).分别写出采用两种方案购买时付款数与领带条数x之间的函数关系式;

(2)就领带条数x讨论在上述方案中采用哪种方案购买合算.

答案

(1)y I=200×20+(x-20)×40=40x+3200(x≥20)(2分).

y II=200×20×90%+x×40×90%=36x+3600(x≥20)(2分).

(2)当y I=y II时,40x+3200=36x+3600,

解得x=100(2分).

即:买100条领带时,可采用两种方案之一(2分).

购买领带超过100条时,采用方案二购买合算(2分).

购买领带20条以上不超过100条时,采用方案 I购买合算(2分)

单项选择题
阅读理解

阅读理解。

     From the first use of the rocket to carry satellites into space to the setting up of space

stations,human beings have been putting great effort into space research.And so far,we have

achieved many successes.But there are still numerous tasks in front of us and we should not

cease trying to progress.

     The international space station is an important step we should take in space exploration.

It is not only helpful but also essential.It provides a proper space environment for many

experiments that we have wanted to do for a long time.It is also a base for the observations

of the earth and the universe.It could also be an important base for later travels to the

moon and Mars.In a word,if we want to explore space more,the first thing we should do

is to set up a space station.

     As the space station costs a lot of money,it is hard for one country alone to establish

one.The USA seems to be the only country that has the ability to build a space station alone,

and it has tried to do so,but not very successful.So it aggregated many other countries to

work on it together.Though it is still extremely expensive,it is much cheaper than doing it

alone.It is really a job that needs everyone's effort and will benefit everyone.

     But even so,the funds needed are still a big problem.As for the USA,it seems that it has

too many things to spend its money on.Although it is the richest country in the world,it has

much debt every year.It has to make arrangements about its finance,and try to find a balance

in all these issues.

1.What is the author's attitude towards building and developing the international space station?

A.Supportive.

B.Doubtful.

C.Critical.

D.Dissatisfied

2.From Paragraph 2 we learn that________.

A.the necessity of building the international space station is not realized now

B.many experiments have been done in the international space sation

C.the international space station is necessary for people to explore space more

D.people have traveled to Mars from the international space station

3.Which of the following is NOT a reason for countries' cooperation in building the

international space station?

A.That it requires a lot of money.

B.That it needs everyone's effort.

C.That it will benefit every participating country.

D.That it is too far away from the earth.

4.The underlined word"aggregated"in Paragraph 3 can be replaced by"________".

A.united

B.scolded

C.allowed

D.forbade

5.Which of the following aspects about building the international space station is NOT

 mentioned in the passage?

A.Difficulties.

B.Cooperation.

C.Significance.

D.Specific arrangements.