题目
What is the limit of the CDF as x tends to infinity?
选项
A.Less than 1.0
B.Equal to 1.0
C.Greater than 1.0
D.Depends on the degrees of freedom
答案
B
解析
It is part of the definition of a probability distribution that the area under the curve equals 1.0;i.e., CDF(x tends to infinite) = 1.0.Various degrees of freedom will impact peak/tail but will not change the probability distribution.曲线下的面积等于1.0;即CDF（x趋于无穷大）= 1.0是概率分布定义的一部分。各种自由度将影响峰/尾，但不会改变概率分布。