對全國各鐵路交通樞紐的貨運量、貨物種類等進行調查，以了解全國鐵路貨運概況。這種調查屬于（）

對某班級學生的生活狀況進行統計調查，下列標志中屬于不變標志的是（）

One advantage of a stem and leaf plot over a frequency distribution is that （）.

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 （）.

什么是季節(jié)變動？研究它的意義何在？如何測定季節(jié)變動？

If the individual class frequency is divided by the total frequency, the result is the （）.

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（）

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

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). The average number of absences per employee, calculated from the personnel data of all employees, is a （）.

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？