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 （）.

某企业2018年技术工占50%，2019年新招收了一批学徒工，使学徒工的比重增加了10%。假定全厂各级工资水平均无变化，则2019年职工总平均工资将（）

什么是季节变动？研究它的意义何在？如何测定季节变动？

Descriptive statistics deals with methods of（）

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

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（）

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

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（）

常用的长期趋势测定的方法有哪些？各有什么特点？

Which of the following is best to show the percentage of a total budget that is spent on each category of items？（）