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

一個地區(qū)一定時期的商品零售額屬于（）

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

以2000年a0為最初水平，2016年an為最末水平，計算鋼產(chǎn)量的年平均發(fā)展速度時，須開（）

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 approximate range of the number of phone calls arriving each hour？（）

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

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 （）.

變量數(shù)列中，各組頻率之和應（）

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 （）.

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