Statement Scale and Representative Fraction: Definition, Differences, and Examples
A map is one of the most important tools in geography. Because the Earth is extremely large, it is impossible to represent its vast geographical features on paper without reducing their size. Therefore, maps use a specific ratio known as the map scale to represent real-world distances in a reduced form.
There are several methods used to express map scales. Among them, two of the most commonly used methods are the Statement Scale and the Representative Fraction (R.F.). These methods help readers understand the relationship between the distance shown on the map and the actual distance on the Earth’s surface.
Definition of Statement Scale
A Statement Scale expresses the relationship between map distance and actual ground distance in words or sentences. It simply tells the reader how much real-world distance is represented by a specific length on the map.
Examples
1 inch = 1,000 miles
2 cm = 1 kilometer
In this method, the scale is written in descriptive form, making it easy to understand.
Definition of Representative Fraction (R.F.)
A Representative Fraction (R.F.) expresses the relationship between the distance on a map and the actual distance on the ground in the form of a ratio or fraction.
Examples
1 : 50,000
1 : 100,000
In this method, both parts of the ratio must be expressed in the same unit.
For example, 1 : 50,000 means 1 unit on the map represents 50,000 of the same units on the ground.
Differences Between Statement Scale and Representative Fraction (R.F.)
| Statement Scale | Basis of Difference | Representative Fraction (R.F.) |
|---|---|---|
| Map distance and actual distance are expressed in words. | Definition | Map distance and real distance are expressed as a ratio or fraction. |
| Written in sentence form. | Method of expression | Written as numerical ratio or fraction. |
| The two parts may have different units. | Unit | Both parts must use the same unit. |
| It may require conversion when measurement systems differ between countries. | Measurement system | It is universally applicable without conversion. |
| Less commonly used in scientific mapping. | Usage | Widely used in cartography and scientific maps. |
Converting Statement Scale into Representative Fraction
Example 1
Statement scale: 1 inch = 6 miles
6 miles = 6 × 63,360 = 380,160 inches [1 mile = 63,360 inches]
Therefore, R.F. = 1 : 380,160
Example 2
Statement scale: 5 inches = 1 mile
1 mile = 63,360 inches
5 inches represent 63,360 inches
1 inch represents 63,360 ÷ 5 = 12,672 inches
Therefore, R.F. = 1 : 12,672
Example 3
Statement scale: 1 cm = 1 kilometer
1 kilometer = 100,000 cm
Therefore, R.F. = 1 : 100,000
Example 4
Statement scale: 4 cm = 1 kilometer
1 kilometer = 100,000 cm
4 cm = 100,000 cm
1 cm = 100,000 ÷ 4 = 25,000
Therefore, R.F. = 1 : 25,000
Determining Statement Scale from Representative Fraction (R.F)
Example – 1:
Suppose R.F = 1 : 63,360. We know that 1 mile = 63,360 inches. Therefore, if the distance on the map is 1 inch, the corresponding distance on the ground will be 63,360 inches, which equals 1 mile. Hence, the statement scale will be: 1 inch on the map = 1 mile on the ground.
Example – 2:
Suppose R.F = 1 : 5,000. This means 1 centimeter on the map represents 5,000 centimeters in reality. We know that 100 centimeters = 1 meter. So, converting 5,000 centimeters into meters gives 50 meters. Therefore, the statement scale becomes: 1 cm on the map = 50 meters on the ground.
Example – 3:
Suppose R.F = 1 : 8,000,000. This means 1 centimeter on the map represents 8,000,000 centimeters in reality. We know that 1 kilometer = 100,000 centimeters. Converting 8,000,000 centimeters into kilometers gives 80 kilometers. Therefore, the statement scale will be: 1 cm (centimeter) on the map = 80 kilometers on the ground.
Understanding map scales is essential for interpreting maps correctly. Both Statement Scale and Representative Fraction play an important role in explaining the relationship between map distance and actual ground distance.
The statement scale presents the relationship in simple words, making it easier for beginners to understand. On the other hand, the representative fraction provides a more precise and universally accepted method used widely in cartography and geographical studies.
Therefore, a clear understanding of these two types of map scales is essential for students and researchers studying geography and map interpretation.
Frequently Asked Questions (FAQ)
A. What is a statement scale in geography?
A statement scale expresses the relationship between map distance and real-world distance in words, such as 1 inch equals 1 mile.
B. What is a representative fraction (R.F.)?
Representative fraction is the ratio between map distance and ground distance expressed in numerical form, such as 1:50,000.
C. What is the difference between statement scale and representative fraction?
Statement scale expresses the relationship in words, while representative fraction expresses it as a numerical ratio where both units are the same.
D. Why is representative fraction widely used in maps?
Representative fraction is widely used because it is universal and independent of measurement systems used in different countries.
E. How is the statement scale determined from the Representative Fraction (R.F)?
First, both sides of the R.F are considered in the same unit. Then the actual ground distance is converted into a larger suitable unit (such as meters, kilometers, or miles). Finally, it is expressed in a sentence form, for example: 1 cm on the map = a certain distance on the ground.
References
- Certificate Physical and Human Geography, Goh Cheng Leong — Oxford University Press.
- Practical Geography, R. L. Singh and P. K. Dutt.
- Elements of Practical Geography, R. L. Singh.
- Geography and Environment textbooks for secondary and higher secondary levels, National Curriculum and Textbook Board (NCTB), Dhaka, Bangladesh.
- Applied and Practical Geography, Abdul Rauf Kazi and Abul Mahmud Kazi, Sujoneshu Publications, Dhaka, Bangladesh.
✍️ Author : Md Shahin Alam
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