问题 解答题
为了了解初三毕业班学生一分钟跳绳次数的情况,某校抽取了一部分初三毕业生进行一分钟跳绳次数的测试,将所得数据进行处理,可得频率分布表.
组别分组频数频率
189.5~99.540.04
299.5~109.530.03
3109.5~119.5460.46
4119.5~129.5bc
5129.5~139.560.06
6139.5~149.520.02
合计a1.00
(1)这个问题中,总体是______;样本容量a=______;
(2)第四小组的频数b=______,频率c=______;
(3)若次数在110次(含110次)以上为达标,试估计该校初三毕业生一分钟跳绳次数的达标率是多少?
(4)在这次测试中,学生跳绳次数的中位数落在哪个小组内?
答案

(1)根据总体、样本容量的概念:可得总体为初三毕业班学生一分钟跳绳次数的全体.

样本容量a=100;

(2)c=1-0.02-0.06-0.46-0.03-0.04=0.39,b=100×0.39=39;

(3)分析可得:样本中,有93人达标,故达标率为93%,则该校初三毕业生一分钟跳绳次数的达标率也为93%;

(4)根据题意可得:学生跳绳次数的中位数为第50和第51个数的平均数,故其中位数落在第3小组.

选择题
问答题

(46) History tells us that in ancient Babylon, the cradle of our civilization, the people tried to build a tower that would reach to heaven. But the tower became the tower of Babel, according to the Old Testament, when the people were suddenly caused to speak different languages. In modern New York City, a new tower, that of the United Nations Building, thrusts its shining mass skyward. (47) But the realization of the UN’s aspirations—and with it the hopes of the peoples of the world—is threatened by our contemporary Babel: about three thousand different languages are spoken throughout the world today, without counting the various dialects that confound communication between peoples of the same land.

In China, for example, hundreds of different dialects are spoken; people of some villages have trouble passing the time of day with the inhabitants of the next town. In the new African state of Ghana, five million people speak fifty different dialects. In India more than one hundred languages are spoken, of which only fourteen are recognized as official. To add to the confusion, as the old established empires are broken up and new states are formed, new official tongues spring up at an increasing rate.

In a world made smaller by jet travel, man is still isolated from many of his neighbors by the Babel barrier of multiplying languages. Communication is blocked daily in scores of ways. Travelers find it difficult to know the peoples of other nations. Scientists are often unable to read and benefit from the work being carried on by men of science in other countries. (48) The aims of international trade, of world accord, of meetings between nations, are blocked at every turn; the work of scholars, technologists, and humanists is handicapped. Even in the shining new tower of the United Nations in New York, speeches and discussions have to be translated and printed in the five official UN language—English, French, Spanish, Russian and Chinese. Confusion, delay, suspicion, and hard feelings are the products of the diplomatic Babel.

The chances for world unity are lessened if, in the literal sense of the phrase, we do not speak the same language. (49) We stand in dire need of a common tongue, a language that would cross national barriers, one simple enough to be universally learned by travelers, businessmen, government representatives, scholars, and even by children at school.

Of course, this isn’t a new idea. Just as everyone is against sin, so everyone is for a common language that would further communication between nations. (50) What with one thing and another—our natural state of drift as human beings, our rivalries, resentments, and jealousies as nations—we have up until now failed to take any action. I propose that we stop just talking about it, as Mark Twain said of the weather, and do something about it. We must make the concerted, massive effort it takes to reach agreement on the adoption of a single, common auxiliary tongue.

(50) What with one thing and another—our natural state of drift as human beings, our rivalries, resentments, and jealousies as nations—we have up until now failed to take any action.