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 （）.

对全国各铁路交通枢纽的货运量、货物种类等进行调查，以了解全国铁路货运概况。这种调查属于（）

什么是季节变动？研究它的意义何在？如何测定季节变动？

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

A cumulative frequency distribution would provide（）.

一个地区一定时期的商品零售额属于（）

要了解某地区全部大学生的就业情况，那么（）

A cumulative frequency polygon is also called （）.

某企业的生产计划完成百分比采用如下分组，请指出哪项是正确的（）

Claudia Taylor, Director of Global Industrial Sales in Melbourne, is concerned by a deteriorating sales trend. Specifically, the number of customers is stable at 1500 but they are purchasing less each year. She orders her staff to search for causes of the downward trend by selecting a focus group of 40 industrial customers. For this study, the set of 40 industrial customers is a （）.