The scale of the map in representative fraction(RF) is

Assessment: JAMB UTME - Geography - 2025 Subject: Geography

Question 1 Report

The scale of the map in representative fraction(RF) is 

Answer Details

A Representative Fraction (RF) expresses a map scale as a ratio with no units: 1 unit on the map represents a certain number of the same units on the ground. To determine the RF from a map, you use the linear (bar) scale printed on the map and measure how many centimetres on the map correspond to a known ground distance.

The map of Abada District includes a linear scale bar at the bottom. By examining the scale bar, 2 cm on the map corresponds to 1 km on the ground. Converting to the same unit:

\[ 1 \text{ km} = 1{,}000 \text{ m} = 100{,}000 \text{ cm} \]

So if 2 cm on the map represents 100,000 cm on the ground:

\[ 1 \text{ cm on map} = \frac{100{,}000}{2} = 50{,}000 \text{ cm on ground} \]

The RF is therefore 1:50,000. This means 1 cm measured on the map equals 50,000 cm (or 0.5 km) on the actual ground.

A common error is misreading the scale bar divisions or making a unit conversion mistake. For instance, forgetting to divide by the number of centimetres measured on the bar scale would give 1:100,000, which is too small a scale. Similarly, doubling the ratio in the wrong direction would give 1:25,000, which would mean the map shows features at twice the detail it actually does.

When converting a linear scale to RF, always measure the bar scale length in centimetres, convert the ground distance to the same unit (centimetres), and then express the ratio as 1 : (ground cm per 1 map cm).

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