I'm 16, and I've been 5'10 since I was 14 too. I've ranged from 165 to 145. Any of this is a good weight, though for me, I am happiest at 145 - 150. That puts me at a size 8 pants, size 6/medium shirt.
The answer depends on the girl's age.
Depends, mainly on gender and age.
Your weight is perfectly normal. You don't need to lose any.
The average weight for a 138 cm girl will vary based on muscle and fat content regardless of age. The average weight is probably around 100 pounds.
it depends on how tall you are, not really your age
Weight varies with height. Age and sex don't target any number.
Weight is worked out on height not age.
The average age for menarche for girls is under 13 years of age. However, individually speaking that can vary depending on several factors including weight.
The average UK height and weight for a 12 year old girl is 4 ft 9 in and 91.5 lbs. The average height and weight for a boy of the same age is 4 ft 8 in and 88 lbs.
It's relative to your age, but it should be between 9.5-10 stone.
The average weight would be 100-120 pounds depending on your BMI. And you shouldn't worry about that at age 13 anyways! :)
For a girl age 10 years average height 138 cm with an average weight range from 21 to 58 kgs.