It is not that simple and answer as it is dependent on one's frame size -small, medium or large bone structure. Also it depends on BMI (Body Mass Index) and/or relative athletic conditioning, as muscle weighs more than fat. Athletes have less fat and, as such, have a different weight chart criteria.
Sorry if this makes matters a bit more complicated.
A simple answer for a 162 cm (5 ft 5-1/2 in), 15 yr old girl, medium build is a range of between 50 Kg(110 lbs) and 62Kg (135 lbs).
I see that by the BMI charts for a medium-framed young lady, optimal weight might be closer to 50-53 kg. However, weighing more than that is still considered healthy, too.