Question

the scale of a map is 1 cm : 75 km. if a river on the map is 4 cm long, how long is the actual river? ? km

Explanation:

Step1: Identify the scale ratio

The scale is 1 cm represents 75 km.

Step2: Set up a proportion

Let $x$ be the actual length of the river. We have $\frac{1}{75}=\frac{4}{x}$.

Step3: Cross - multiply and solve

$1\times x = 75\times4$. So $x = 300$.

Answer:

300