题目
Which of the following are characteristics of a normal distribution? I.Skewness equals to zero. II.Mean less than median. III.Kurtosis greater than zero. IV.Continuous and unbounded.
选项
A.I and IV
B.II and III
C.I, II and III
D.I, III and IV
答案
D
解析
The characteristics of a normal distribution are: It is a continuous distribution. It is bell shaped. It is symmetrical about the mean. It peaks at the mean expected value. It extends theoretically from negative infinity to positive infinity (the probability asymptotically approaches zero at plus and minus infinity). It has a skewness of zero. It has a kurtosis of three. 正态分布的特征是： 这是一个连续的分布。 它是钟形的。 它关于均值是对称的。 它在平均期望值上达到峰值。 理论上，它从负无穷大到正无穷大（正负无穷大渐近接近零的概率）。 它的偏度为零。 它具有三个峰度。