Average for a an 11 year old girl is 9:30 so you are doing beyond average, you are in the 80th percentile. Boys run faster because they have more testosterone, a hormone that makes them bigger and stronger. The average time for an 11 year old boy is 8:30.
im 11 and at best i got 4:45. guys just work at it too look cool :)
When I was 11 I ran like 7 minutes... and I was the best in my grade! Haha. Your really good! And if that boy tries to brag about being faster than you, tell him that boys are SUPPOSED to be faster than girls... it's something about their body structure