Of course, if the average is 13, then then 1/2 of the girls will be younger than that. This is not true: you have confused the average and the median. In this case, they may have significantly different values.
Do try to be civil when you post.
Of course, if the average is 13, then then 1/2 of the girls will be younger than that. This is not true: you have confused the average and the median. In this case, they may have significantly different values. Yes, sorry. The point is that there always have been, and always will be exceptions to the average. Anecdotal evidence that some girls develop at 9 does not mean that the average is going down.