Claudia Taylor, Director of Global Industrial Sales in Melbourne, is concerned by a deteriorating sales trend. Specifically, the number of customers is stable at 1500 but they are purchasing less each year. She orders her staff to search for causes of the downward trend by selecting a focus group of 40 industrial customers. For this study, the set of 40 industrial customers is a （）.

If data are grouped into intervals and the number of items in each group is listed, this could be called a （）

A cumulative frequency polygon is also called （）.

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？（）

如果居民按报告期价格购买商品需多支出40万元，报告期商品销售额为200万元，则价格指数为（）

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

企业生产一种产品需顺次经过四个车间，这四个车间的废品率分别为1.5%、2.0%、2.0%和1.0%。该企业生产这种产品的平均废品率是多少？

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 （）.

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

最能反映离散程度的指标是（）