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

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

Which of the following statements is not true？（）

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

時間序列構(gòu)成因素有哪些？分解的基本原理和思路是什么？

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（）

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 （）.

A cumulative frequency polygon is also called （）.

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

什么是季節(jié)變動？研究它的意義何在？如何測定季節(jié)變動？