Question

the VI is 30m and the HE on a 1:30000 map is 75mm, calculate the gradient

Answer 1

75 mm is 7.5 cm. 1:30000 means that 1 cm om map is 30 000 cm in the real world, or 300 m. Therefore, the HE is 7.5·300=2250 m.

Thus, the gradient is

$$\text{grad}=\frac{VI}{HE}=0.013,\text{ or 1.3}\%.$$