The scale of the model is 5 cm : 2 m. This means that for every 5 cm on the model, the actual length is 2 m.
If the length of the model is 48 cm, we can set up a proportion to find the actual length of the old wagon:
5 cm (actual length) / 2 m = 48 cm (model length) / x (actual length)
where x is the actual length of the old wagon.
To solve for x, we can cross-multiply and simplify:
5 cm * x = 2 m * 48 cm
5 cm * x = 96 cm
Dividing both sides by 5 cm, we get:
x = 96 cm / 5 cm
x ≈ 19.2 m
Therefore, the actual length of the old wagon is approximately 19.2 meters.