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A Handbook for Beginners to Simplifying Proportional Concepts
Solving the Proportional Mysteries - What Hidden Truths Lie in Thirds, Fourths, and Means?

04 Jan A Handbook for Beginners to Simplifying Proportional Concepts

A key idea that forms the cornerstone of the relationship between quantities is proportions, intricately woven throughout the complex fabric of mathematics. These proportions reveal equilibrium of ratios, presenting a world of balance and consistency amidst fluctuating magnitudes. As we navigate the depths of these proportional relationships, we embark on a journey into the enigmatic realms of third, fourth, and mean proportional, uncovering the profound intricacies nestled within these mathematical phenomena. Exploring these concepts is made accessible and enriching with the guidance of our Maths tuition, providing a tailored approach to understanding these fundamental principles.

Proportion: What Is It?

Proportion lies at the heart of comparing quantities, establishing harmony between different values. It embodies the relationship where two ratios maintain an equilibrium, signifying that their relative sizes remain constant even as they change in magnitude. Essentially, it’s the balanced interplay between quantities, revealing how they relate and interact with each other in a consistent manner.

How should a proportion be represented?

Expressing a proportion involves illustrating the relationship between two sets of quantities or ratios. This equality can be depicted in multiple formats:

  •         a : b :: c : d
  •         a/b = c/d
  •         a is to b as c is to d

Here, the ratio of ‘a’ to ‘b’ is equal to the ratio of ‘c’ to ‘d’.

In these representations, the ratios on both sides exhibit an equal relationship, showcasing the proportional balance between the quantities involved.

Formula & Examples of Proportional:

Proportions revolve around the equality of ratios. Imagine two ratios, a/b = c/d. They form a proportion if they’re equivalent. Mathematically, this is expressed as:

  •         If a/b = c/d, then a is to b as c is to d

Here are a couple of examples illustrating this principle:

  •         If 2/4 = 6/12, it forms a proportion since both ratios reduce to 1/2.
  •         However, 3/5 and 6/10 also form a proportion as they both reduce to 3/5.

In essence, when the ratios of two sets of numbers are equal, they establish a proportional relationship, demonstrating a consistent ratio or balance between the quantities involved.

Types of Proportional:

Proportions manifest in diverse ways, showcasing the relationships between quantities. They primarily divide into two fundamental categories: direct and inverse proportion.

Direct Proportion:

In a direct proportion, as one variable increases, the other also increases in a consistent manner. Mathematically, this is expressed as:

If a : b = c : d, then ‘b’ is directly proportional to ‘a’ if b = k x a, where ‘k’ is a constant.

For instance, if the cost of ‘b’ items is directly proportional to the number of items ‘a’ at a constant price ‘k’, then b = k x a.

Inverse Proportion:

Contrarily, an inverse proportion describes a relationship where an increase in one variable results in a decrease in the other, maintaining a constant ratio. Mathematically, this is articulated as:

If a : b = c : d, then ‘b’ is inversely proportional to ‘a’ if b = k/a, where ‘k’ is a constant.

For example, if the time taken ‘b’ to complete a task is inversely proportional to the number of workers ‘a’ allocated to it at a constant efficiency ‘k’, then b = k/a.

Third, Fourth & Mean Proportional:

In the realm of proportions, third, fourth, and mean proportional play distinctive roles, showcasing the interrelatedness of quantities within mathematical equations. Let’s explore these proportional relationships in-depth.

Third Proportional:

The third proportional in a proportion a : b :: b : x is ‘x’, illustrating a relationship where ‘x’ is the third term proportional to ‘a’ and ‘b’. For instance, if 2 : 3 :: 3 : x, ‘x’ is the third proportional to 2 and 3, thereby making ‘x’ equal to 4.5. Mathematically, it can be expressed as:

Given a : b :: b : x, then

ð  a/b = b/x

ð  x = (b^2) / a.

Fourth Proportional:

The fourth proportional in a proportion a : b :: c : x is ‘x’, demonstrating a relationship where ‘x’ is the fourth term proportional to ‘a’, ‘b’, and ‘c’. For example, if 2 : 3 :: 4 : x, ‘x’ is the fourth proportional to 2, 3, and 4, making ‘x’ equal to 6. The mathematical representation is:

Given a : b :: c : x, then

ð  a/b = c/x

ð  x = (b x c) / a

Mean Proportional:

The mean proportional between two numbers ‘a’ and ‘b’ is represented as ‘x’, where ‘x’ is the square root of their product. For instance, if ‘a’ and ‘b’ are 4 and 9 respectively, the mean proportional is √4 x 9 = 6.

In mathematical terms, it can be expressed as:

Given a: x :: x : b, then

ð  a/x = x/b

ð  x2 = a x b or x = √a x b

Understanding these proportional relationships not only aids in grasping fundamental mathematical concepts but also finds applications in various scientific and practical scenarios.

Properties of Proportion:

  •         Addendo: In a : b = c : d, sum each pair of terms: a + c : b + d.
  •         Subtrahendo: In a : b = c : d, find differences: a – c : b – d.
  •         Dividendo: In a : b = c : d, divide terms: a/b : b = c/d : d.
  •         Componendo: In a : b = c : d, sum and divide: a + b : b = c + d : d.
  •         Alternendo: In a : b = c : d, ratios are preserved: a : c = b : d.
  •         Invertendo: In a : b = c : d, swap and maintain ratios: b : a = d : c.
  •         Componendo and Dividendo: In a : b = c : d, sum and difference of ratios: a + b : a – b = c + d : c – d.

These properties enable various manipulations and comparisons within proportional relationships, highlighting the consistency and balance among the involved quantities.

How Our Maths Tutors Enhance Your Understanding?

Our expert Math tutors at Miracle Learning Centre, renowned for providing the best Maths Tuition in Singapore, significantly elevate understanding of proportional concepts. Through personalized guidance and tailored teaching methods, our Math tutors decode the complexities of proportions with ease. They employ interactive sessions, relatable examples, and diverse learning approaches; ensuring students comprehend the nuances of third, fourth, and mean proportional effectively.

With our specialized Math Tuition, students grasp fundamental principles, master problem-solving techniques, and gain confidence in applying these concepts across various disciplines. At Miracle Learning Centre, our dedicated Math tutors empower students to excel, fostering a deeper understanding of proportional mathematics and paving the way for academic success.


In conclusion, proportions form vital mathematical relationships. Third, fourth, and mean proportional deepen this understanding, aiding problem-solving and paving the way for advanced concepts. With adept tutors in Maths tuition in Singapore, exploring proportional becomes an enriching journey, fostering invaluable analytical skills for diverse disciplines.