none
a thirteen year old should do about 25-40
as many as he/she can, or as many as you teach her/him
5
a fifteen year old should be able to do atleast 110 sit ups in two minutes.
As a fifty year old woman, if you can do one pull-up you're way ahead of most women. The answer is though: do as many as you can, and remember to train your antagonist(push) muscles.
100
10
all five do it
Any where between 25-100.
the Presidentβs Council on Fitness, Sports, and Nutrition has some standards we can go by (Source): Children β 6-12 years of age should be able to perform between 1-2 pull-ups (i.e. 50th percentile).
10-30