Which of the following is not the goal of descriptive statistics?（）

The number of class intervals in a frequency distribution is usually between （）.

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？

One rule that must always be followed in constructing frequency distributions is that （）.

某廠某年職工勞動生產(chǎn)率為20000元，是歷史最高水平的1.2倍。這里的1.2倍是（）

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)（）

企業(yè)生產(chǎn)一種產(chǎn)品需順次經(jīng)過四個車間，這四個車間的廢品率分別為1.5%、2.0%、2.0%和1.0%。該企業(yè)生產(chǎn)這種產(chǎn)品的平均廢品率是多少？

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

為什么在計(jì)算平均指標(biāo)的基礎(chǔ)上還有必要進(jìn)一步計(jì)算變異指標(biāo)？