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？（）

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

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？（）

品合格率指標(biāo)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). The average number of absences per employee, calculated from the personnel data of all employees, is a （）.

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

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？

最能反映離散程度的指標(biāo)是（）

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

常用的長期趨勢測定的方法有哪些？各有什么特點(diǎn)？