What is average time for 12 year old girl to run 800m?

"I am a girl in grade 7(13 years of age) and it takes me 21 seconds to run this and i can run 200 meters in 40 seconds so all you have to do is pratice."

The answer above was posted by another person, but I just wanted to share that I am 13 years old (since January 2010), and I can run 100 meters in 16 seconds. That is one of the best times for that a 7th grader (13 years)girl could run, but when I was 12 last year, I ran 100 meters in about 21 seconds. (but i didn't try hard). 21 seconds is average, though. Other girls in my gym class had 21 seconds.