Question

B) The distance between two places is 18 km. If the map scale is 1:400000, find the

distance between the places in centimetres drawn in the map.​

Answer 1

Map scale is 1:400000 => 1 cm on the map represents 400000 cm (4 km) on the ground.

So, 18 km on the ground is represented by 18/4 cm or 4.5 cm on the map.

Answer: 4.5 cm

Explanation:

The clear and easiest way to deal with this problem is to convert all measurements to centimeters because that is the stated unit to be used. In SI, the metric prefixes can be written as exponents. The prefix kilo corresponds to 10^3 while the prefix centi corresponds to 10^-2 so 18 km = 18 x 10^3 m = 18 x 10^3 x 10^2 cm= 18 x 10^5 cm.

The number 18 x 10^5 cm is to be reduced to 400,000 times in the map and it means a process of division is to be performed. Dividing 18 x 10^5 cm by 400,000 gives a quotient of 4.5 cm.

This means that an actual distance of 18 km, on the map it just corresponds to 4.5 cm distance if the scale used is 1:400,000.