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

品合格率指標(biāo)是（）

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

對(duì)某班級(jí)學(xué)生的生活狀況進(jìn)行統(tǒng)計(jì)調(diào)查，下列標(biāo)志中屬于不變標(biāo)志的是（）

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 （）.

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？（）

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

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

某企業(yè)的生產(chǎn)計(jì)劃完成百分比采用如下分組，請(qǐng)指出哪項(xiàng)是正確的（）

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