1 doctor weighed in:

What is an average weight for a 15 year old girl about 5ft?

1 doctor weighed in
Dr. Clarene Cress
Pediatrics

In brief: 105 pounds

would be about the 50%, but age of menses, body frame and muscularity are all important.
Some girls are still healthy at 85-90#, but over 125# would be at the highest recommended weight for that height. If you are wanting to lose weight, please talk with your doctor first, who can help you find what's best for you. Weight loss can spiral and lead to anorexia and serious health problems.

In brief: 105 pounds

would be about the 50%, but age of menses, body frame and muscularity are all important.
Some girls are still healthy at 85-90#, but over 125# would be at the highest recommended weight for that height. If you are wanting to lose weight, please talk with your doctor first, who can help you find what's best for you. Weight loss can spiral and lead to anorexia and serious health problems.
Thank