品合格率指标是（）

单项选择题某厂某年职工劳动生产率为20000元，是历史最高水平的1.2倍。这里的1.2倍是（）

A.比例相对数
B.计划完成相对数
C.强度相对数
D.动态相对数

单项选择题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.80
B.200
C.20
D.100

单项选择题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？（）

A.80
B.0.40
C.155
D.75

单项选择题A cumulative frequency distribution would provide（）.

A.a graph of a frequency distribution
B.a running total of the frequencies in the classes
C.the proportion of the total frequencies which fall into each class
D.a very cloudy picture of the frequencies

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

A.histogram
B.ogive
C.stem and leaf chart
D.pie chart