自由度决定什么呢？他的增加改变了高度？问题如下图：
选项：
A. 
B. 
C. 
D. 
解释：
NO.PZ2016062402000014 问题如下 Whiof the following statements is the most accurate about the relationship between a normstribution ana Stunt’s t stribution thhave the same meanstanrviation? A.They have the same skewness anthe same kurtosis. B.The Stunt’ t stribution hlarger skewness anlarger kurtosis. C.The kurtosis of a Stunts t stribution converges to thof the normstribution the number of grees of freem increases. The normstribution is a gooapproximation for the Stunt’s t stribution when the number of grees of freem is small. The two stributions have the same skewness of zero but the Stunt’ t hlower kurtosis. the number of grees of freem increases, the Stunt’s t stribution converges to the normstribution, so C is the correanswer. t分布正常是比正态分布离散的，题目里说T和Z方差一致时，我理解就是n已经大到T趋近于Z的情况了，为什么A不对呢
NO.PZ2016062402000014 The Stunt’ t stribution hlarger skewness anlarger kurtosis. The kurtosis of a Stunts t stribution converges to thof the normstribution the number of grees of freem increases. The normstribution is a gooapproximation for the Stunt’s t stribution when the number of grees of freem is small. The two stributions have the same skewness of zero but the Stunt’ t hlower kurtosis. the number of grees of freem increases, the Stunt’s t stribution converges to the normstribution, so C is the correanswer.老师，按照T分布的峰度公式，3（n-2)/(n-4)，不是应该大于3吗？应该比这正态分布的峰高才是啊，为什么是低峰肥尾呢？
正态分布与t分布，在两者的均值与标准差相同的时候，相对于正态分布，t分布峰度低，并且尾部肥，对吗？那么，在讲Kurtosis的时候，假设方差相同，得出的结论是低峰→薄尾。不矛盾吗？请问老师，我是哪里理解错了？
老师你好，请问什么不对呢？增大，t分布趋近于Z分布，过来说不可以吗？
