问题如下图：
选项：
A. 
B. 
C. 
解释：
请问哪侧尾巴长？可不可以画出这个的图形。我老是混淆。谢谢！
NO.PZ2015120604000057问题如下Molly is stuing the return stribution of firm A's stock. She fin ththe meof storeturns is smaller ththe mean. Whiof the following statements about the return stribution is correct? A.The return stribution is positively skeweB.The return stribution is negatively skeweC.The return stribution ha positive excess kurtosis.A is correctFor a positively skewestribution, the mo is less ththe mean, anthe meis less ththe mean. There are positive outliers whiwill tento pull the memore positive.之前的提问中，有回答说kurtosis是衡量尾部情况的参数。1.skewness不衡量尾部吗？它的尾部不也是变化的吗（ftail,thin tail）？2.skewness是衡量什么情况的参数呢？
NO.PZ2015120604000057 问题如下 Molly is stuing the return stribution of firm A's stock. She fin ththe meof storeturns is smaller ththe mean. Whiof the following statements about the return stribution is correct? A.The return stribution is positively skewe B.The return stribution is negatively skewe C.The return stribution ha positive excess kurtosis. A is correctFor a positively skewestribution, the mo is less ththe mean, anthe meis less ththe mean. There are positive outliers whiwill tento pull the memore positive. positive excess kurtosis是什么意思呀？怎么判断他是这个呀？
NO.PZ2015120604000057问题如下 Molly is stuing the return stribution of firm A's stock. She fin ththe meof storeturns is smaller ththe mean. Whiof the following statements about the return stribution is correct? A.The return stribution is positively skeweB.The return stribution is negatively skeweC.The return stribution ha positive excess kurtosis.A is correctFor a positively skewestribution, the mo is less ththe mean, anthe meis less ththe mean. There are positive outliers whiwill tento pull the memore positive.C为什么错呢，两者有什么关系
不是小于均值，左侧尾巴啊长吗，不应该是nwgative吗
