证明 http://www.lagriffedulion.f2s.com/math.htm
计算依据的实验数据：
“Project Talent1 study of 1960. It remains one of the best assessments of
cognitive sex differences in a complete age group ever made. The sample was
designed to be representative of all 15 year-olds in the US. It included
more than 73,000 15 year-olds, both students and nonstudents. They were
given an all-day battery of 23 cognitive tests. The mathematics results
revealed a mean (male-female) difference of 0.12 standard deviations2 and a
1.20 (male/female) variance ratio”
