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

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（）

A cumulative frequency polygon is also called （）.

時間序列構成因素有哪些？分解的基本原理和思路是什么？

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

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 （）.

對某班級學生的生活狀況進行統(tǒng)計調查，下列標志中屬于不變標志的是（）

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？

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 （）.

某企業(yè)2018年技術工占50%，2019年新招收了一批學徒工，使學徒工的比重增加了10%。假定全廠各級工資水平均無變化，則2019年職工總平均工資將（）