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？（）

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 （）.

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

一個地區(qū)一定時期的商品零售額屬于（）

Descriptive statistics deals with methods of（）

One advantage of a stem and leaf plot over a frequency distribution is that （）.

If the individual class frequency is divided by the total frequency, the result is the （）.

A cumulative frequency distribution would provide（）.

對全國各鐵路交通樞紐的貨運量、貨物種類等進行調(diào)查，以了解全國鐵路貨運概況。這種調(diào)查屬于（）

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