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 （）.

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

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

最能反映離散程度的指標是（）

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 （）.

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

Which of the following statements is not true？（）

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

某企業(yè)的生產(chǎn)計劃完成百分比采用如下分組，請指出哪項是正確的（）

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？