Question

A particular map shows a scale of 1 cm:7 km. What would the distance on the map be if the actual distance is 21 kilometers?

• A. 2 cm
• B. 3.5 cm
• C. 2.5 cm
• D. 3 cm

Answer 1

The correct option is D 3 cm

Given:
Scale is 1 cm:7 km.
Therefore, map distance:actual distance = 1 cm:7 km
Actual distance = 21 km

Let the distance on the map be $xcm.$
Therefore, $xcm:21km=1cm:7km$
$\Rightarrow \frac{xcm}{21km}=\frac{1cm}{7km}$
$\Rightarrow \frac{x}{21}=\frac{1}{7}$
$\Rightarrow 7x=21$

$\Rightarrow \frac{7x}{7}=\frac{21}{7}$ (Dividing both sides by 7)
$\Rightarrow x=3cm$