标准方差的一道题，请大家看看

logowuyi

Q3:
Is the standard deviation of the salaries of Company Y’s employees greater than the standard deviation of the salaries of Company Z’s employees?
(1)    The average (arithmetic mean) salary of Company Y’s employees is greater than the average salary of Company Z’s employees.
(2)    The median salary of Company Y’s employees is greater than the median salary of Company Z’s employees.
   
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
答案是E。关于标注方差，我中学时没学过，一点都不会。现在看到标注方差（和正态分布）的题就头疼，请大家帮帮忙，谢谢！

logowuyi

谢谢LS两位的细心讲解，现在我明白了！

logowuyi

Ls, D是说2个条件中任何一个都可以推出结论。E说2个条件加在一起都不能推出结论。两个明显不同，不可能同时正确。