标准方差的计算公式是：
每一个数与这个数列的平均值的差的平方和，除以这个数列的项数，再开根号
分析：
标准方差主要和分母、分之有直接关系
这里的偏差为每一个数与平均值的差。
几个适用的理解：
1.数据分布离平均值越近，GMAT数学标准方差越小;数据分布离平均值越远，标准方差越大。
2.标准方差为0，意味着数列中每一个数都相等。
3.序列中每一个数都加上一个常数，标准方差保持不变的
4.序列中每一个数都乘以不为0的数N，标准方差扩大N倍
上一篇： GMAT数学经典习题举例分析
下一篇： GMAT数学如何有效提速
体坛英语资讯：Russia edge hosts Germany to face Czechs in ice hockey worlds final
体坛英语资讯：French top player Tsonga makes through five-set first round
体坛英语资讯：German defender Westermann to miss World Cup in South Africa
体坛英语资讯：Japans Nakamura injury doubt for World Cup warmup against England
体坛英语资讯：Beckham invited to help England but no coaching
体坛英语资讯：Dutch squad for World Cup
体坛英语资讯：Portugal defender Pepe cleared to play World Cup
体坛英语资讯：Spain coach Del Bosque looking ahead after warm-up win
体坛英语资讯：DPRK downs China 1-0 in extra time to reach Asian Cup final
体坛英语资讯：Bolt quits New York meet due to minor injury
体坛英语资讯：Czech win trophy at ice hockey worlds
体坛英语资讯：Italys Nibali wins 14th stage of Giro dItalia
体坛英语资讯：Safina suffers early exit at French Open
体坛英语资讯：China enjoys strong start at Moscow table tennis team worlds
体坛英语资讯：Nadal moves on, Roddick ousted at French Open
体坛英语资讯：South Africa refutes World Cup terror report
体坛英语资讯：Brazils president bid farewell to World Cup squad
体坛英语资讯：FIFA World Cup finalists face doping tests
体坛英语资讯：Real Madrid presents Jose Mourinho as new coach
体坛英语资讯：Onyewu, Buddle back to U.S. squad
体坛英语资讯：French Open could be moved out of Paris in 2016
体坛英语资讯：Federer enjoys rain, Kuznetsova escapes defeat at French Open
体坛英语资讯：Defending champion Kuznetsova ousted at French Open
体坛英语资讯：Milito fires Inter Milan and Mourinho to Champions League glory
体坛英语资讯：Federer, Serena win opening matches at French Open
体坛英语资讯：Chinas Liu Xiang unsure about London Olympics
体坛英语资讯：South Africa thrash Guatemala at World Cup warmup
体坛英语资讯：Top seeds move on at French Open
体坛英语资讯：Woods confirms to attend Memorial tourney
体坛英语资讯：Real Madrid sacks coach Pellegrini and will contract Jose Mourinho