My Major was Psychology I am familiar with statistics we encounter them all the time, and the numbers are not working out the way you have detailed them. You would have two bell curve distributions for male and female with an 80% overlap. Which given what I know about human nature makes intuitive sense, we as a species largely overlap in average distribution in most attribute details, cognitive and physical.
It would not surprise me that in the US the numbers would turn out different given the ongoing obesity epidemic inflicting both males and females, that must skew the numbers.
Fun conversation. I couldn't help chiming in on this topic given my university major and interest in human nature.
Respect your good manners, and the respectful way you have conducted yourself in this thread.
Edit:
Have been doing a bit of research into this topic.
As a general rule from what I have found women are roughly 2/3rds as muscularly strong comparative to men. Meaning the overlap of the gender bell curves would be roughly 70%. The initial 20% you mentioned falls close to that range of distribution and the 2/3rds estimate is a good approximation. The largest difference falls in upper body strength..
I think body muscle comparisons are more revealing than strict body mass comparisons, because males and females contain different average fat to muscle ratios and even different ratios of differing types of muscle fibers.
"a woman's body is typically about 30 to 35 percent muscle by weight, while a man's body is about 40 to 50 percent muscle by weight".
The difference in average musculature is more stark when comparing the upper body of each sex, a European study found that "the women were approximately 52 percent and 66 percent as strong as men in the upper and lower body respectively."
This study only had 16 male and 16 female subjects, which is a very small sample to draw broad conclusions from and thus will have had a very large margin of error. I would take these findings with a grain of salt, the precise numbers are worthy of skepticism given the tiny sample size.
It has also been said that the type of muscles differ and that women tend to have more slow twitch muscles.
"Perhaps most notably, women tend to have about 27 to 35 percent more type I muscle fibers than men. More commonly known as
slow-twitch muscle fibers, as per the
American Council on Exercise, type I fibers are aerobic muscles rich in blood-carrying myoglobin. By the same token, women's muscles have a greater capillary density.
The combo of more slow-twitch fibers and more capillaries makes for an increased ability to deliver more blood to the muscle, while it also increases fatty acid oxidation.
According to ACE, "Because they can provide their own source of energy, slow-twitch fibers can sustain force for an extended period of time, but they are not able to generate a significant amount of force"."
So it seems that women may have on average greater muscle endurance over time, although lower capacity to exert immediate force. This makes some sense to me, given our species history and what I have learnt of early hunter gatherer societies during the vast majority of our history.