Given that the scale on a map is 1:480,000. Find the actual distance on the ground in kilometres by 4 centimetres on a map.

The scale 1:480,000 means that 1 unit on the map represents 480,000 units on the ground. Since the map distance is given in centimetres, 1 cm on the map represents 480,000 cm on the ground.

The distance on the map is 4 cm.

We know that $1 \text{ m} = 100 \text{ cm}$ and $1 \text{ km} = 1000 \text{ m}$.
Therefore, $1 \text{ km} = 1000 \times 100 \text{ cm} = 100,000 \text{ cm}$.
To convert centimetres to kilometres, divide by 100,000.

The actual distance on the ground is $19.2 \text{ km}$.