Question

Difficulty: MediumMap Scale Conversion and Distance Calculation

A surveyor measures a straight stretch of road between two agricultural settlements on a topographical map drawn to a scale of 1:75,0001 : 75,000. If the distance between the two settlements on the map is 16 cm16\text{ cm}, what is the actual ground distance in kilometers?

Answer: 12 km

Answer

The actual ground distance between the two settlements is 12 km12\text{ km}.
A Representative Fraction scale of 1:75,0001 : 75,000 means 1 cm1\text{ cm} on the map represents 75,000 cm75,000\text{ cm} on the ground. Converting 75,000 cm75,000\text{ cm} into kilometres gives 75,000100,000=0.75 km\frac{75,000}{100,000} = 0.75\text{ km}. Multiplying the measured map length of 16 cm16\text{ cm} by 0.75 km/cm0.75\text{ km/cm} yields an actual distance of 12 km12\text{ km}.

Step-by-Step Solution

1
Convert scale denominator from centimetres to kilometres
1 cm on map=75,000 cm on ground=0.75 km1\text{ cm on map} = 75,000\text{ cm on ground} = 0.75\text{ km}
Dividing centimetres by 100,000100,000 (100 cm/m×1,000 m/km100\text{ cm/m} \times 1,000\text{ m/km}) converts centimetres to kilometres.
2
Calculate the actual ground distance
16 cm×0.75 km/cm=12 km16\text{ cm} \times 0.75\text{ km/cm} = 12\text{ km}
Multiplying the measured distance on the map by the ground distance represented per centimetre gives the total ground distance.

Key Concept

Map Scale Conversion and Ground Distance Calculation
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