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

變量數(shù)列中，各組頻率之和應(yīng)（）

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

企業(yè)生產(chǎn)一種產(chǎn)品需順次經(jīng)過四個(gè)車間，這四個(gè)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？

要了解某地區(qū)全部大學(xué)生的就業(yè)情況，那么（）

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)？

在組距數(shù)列中，下限就是（）

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？（）

一個(gè)地區(qū)一定時(shí)期的商品零售額屬于（）

A student achieves an 82 on the first test in a statistics course. From this, she assumes that her average at the end of the semester (after other tests) will be about 82. This is an example of （）.