Simon Arnett, Director of Human Resources, is exploring the causes of employee absenteeism at Buderim Bottling during the last operating year (1 January 2005 to 31 December 2005). Personnel records of 50 employees are selected for analysis. (The plant employs 250.) For this study, the average number days absent for these 50 employees is a （）.

常用的長期趨勢測定的方法有哪些？各有什么特點？

要了解某地區(qū)全部大學生的就業(yè)情況，那么（）

一個地區(qū)一定時期的商品零售額屬于（）

企業(yè)生產一種產品需順次經過四個車間，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)生產這種產品的平均廢品率是多少？

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

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

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

Which of the following statements is not true？（）

品合格率指標是（）