時間序列構(gòu)成因素有哪些？分解的基本原理和思路是什么？

If data are grouped into intervals and the number of items in each group is listed, this could be called a （）

A summary measure that is computed from a sample to describe a characteristic of the population is called（）

要了解某地區(qū)全部大學(xué)生的就業(yè)情況，那么（）

A cumulative frequency polygon is also called （）.

The number of phone calls arriving at a switchboard each hour has been recorded and the following frequency distribution has been developed.What is the approximate range of the number of phone calls arriving each hour？（）

某班的學(xué)習(xí)按考試成績分為60分以下，60-70，70-80，80-90，90-100，這種分組（）

A cumulative frequency distribution would provide（）.

The number of phone calls arriving at a switchboard each hour has been recorded and the following frequency distribution has been developed.What is the cumulative frequency of the third class？（）

變量數(shù)列中，各組頻率之和應(yīng)（）