问题 解答题

一架电梯的最大载重是1000千克. 现有13位 “重量级”的乘客要搭乘电梯,已知其中11位先生的平均体重是80千克,2位女士的平均体重是70千克,请问他们能否一起安全地搭乘这架电梯?他们的平均体重是多少千克?    

小飞的解答:11位先生的总体重=80×11=880 (千克)    2位女士的总体重=70×2=140(千克)    13位乘客的总体重=880+140=1020(千克)    因为总体重超过了电梯的最大载重,所以他们不能一起安全地搭乘,平均体重是(80+70)÷2=75(千克)

你怎样评价小飞的解答?只有在什么情况下才可以采取这种策略求平均数?

答案

解:小飞的解答中,求平均体重是错的

13位乘客的平均体重为 1 020÷l3≈78.5(千克).

只有当两组数据的数据个数相同时. 这种策略才可行.

单项选择题
阅读理解

C

At present, in many American cities expecially, many teachers in the public schools say they are underpaid. They point to jobs such as secretary or truck driver, which often pay more to start than that of a teacher. In many other fields, such as law, medicine, computer science, a beginning worker may make more than a teacher who has taught for several years.

Teaching has never been a profession that attracted people interested in high salaries. It is by history a profession that has provided rewards in addition to money—the satisfaction of sharing knowledge, of influencing others, of guiding young people. But in the past several years, there are more difficulties in teaching, for many, than there are rewards.

Unruly students, especially in big cities, large classes and a lack of support from the public in terms of money and understanding have led many public school teachers to leave the profession.

As a result, many of the best students, who would have chosen teaching as their life career in the past, are going into other fields.

Another reason for this change in teacher candidates is the changing status of women in the United States. Until the late 1960s and 1970s, one of the most popular choices for women was teaching. But as other professions, such as law and medicine opened up to women, women stopped pouring into teacher training programs. Thus, a major pool of excellent candidates for the teaching profession dwindled.

Bit by bit government officials and others realized that the status of the teacher had suffered. They talked about change. But the change in a vast society like the United States is not easy. People’s attitudes have formed over many years, and sometimes change takes many years.

63.The underlined word “that” in Paragraph 1 refers to “      ”.

A.money             B.job

C.secretary          D.truck driver

64.What is the present situation of the teaching?

A.Teachers work harder and get underpaid.

B.Teahcers have no opportunities to work in other fields.

C.Teaching can attract best students to work as a teacher.

D.Teaching can provide rewards as well as high salaries.

65.Many public school teachers turn to other professions because        .

A.the government doesn’t finacially support them

B.they have to work longer hours than a lawyer

C.their students refuse to listen to them

D.they are not fairly treated

66.The author believes that change in teachers’ status in the United States       .

A.is not great     

B.is impossible

C.influences people’s attitude

D.needs time