The number of phone calls arriving at a switchboard each hour has been recorded and the following frequency distribution has been developed.What is the cumulative frequency of the third class？（）

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 （）.

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

如果居民按報(bào)告期價(jià)格購買商品需多支出40萬元，報(bào)告期商品銷售額為200萬元，則價(jià)格指數(shù)為（）

一個(gè)地區(qū)一定時(shí)期的商品零售額屬于（）

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 （）.

品合格率指標(biāo)是（）

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

常用的長期趨勢測定的方法有哪些？各有什么特點(diǎn)？

時(shí)間序列構(gòu)成因素有哪些？分解的基本原理和思路是什么？