Triplicate Ratio: Formula, Rules and Solved Questions

Triplicate Ratio is formed by taking the cubes of the two terms of a given ratio. For a ratio a:b, its triplicate ratio is a³:b³. This page explains the formula, simplification method, reverse calculation and solved examples involving cubed ratios.

On this page

What Is Triplicate Ratio?

The triplicate ratio of a:b is the ratio of the cubes of its terms, written as a³:b³. Thus, the triplicate ratio of 2:3 is 8:27.

To find a triplicate ratio, cube the first term and the second term separately. If the given ratio is m:n, then its triplicate ratio is m³:n³. The terms may be simplified after cubing, although reducing the original ratio first is usually quicker. For example, 4:6 becomes 2:3, and its triplicate ratio is 2³:3³ = 8:27.

Triplicate Ratio Formula & Tricks

Important Formulas

Basic triplicate ratio formula
Triplicate ratio of a:b = a³:b³

Cube each term of the given ratio separately and write the resulting cubes in the same order.

Fraction form
Triplicate ratio of a/b = a³/b³

A ratio a:b can be written as a fraction a/b; cubing the ratio gives a³/b³.

Reverse operation
If A:B = a³:b³, then a:b = ∛A:∛B

Take the cube root of both terms when the given triplicate-ratio terms are perfect cubes.

Quick Tricks

Reduce before cubing

First reduce the given ratio to its simplest form, then cube the smaller terms. This avoids unnecessary large calculations.

Example: For 12:18, first divide by 6 to get 2:3. Therefore, the triplicate ratio is 8:27, not 12³:18³ followed by lengthy simplification.
Use known cubes

Remember common cubes such as 2³ = 8, 3³ = 27, 4³ = 64 and 5³ = 125.

Example: The triplicate ratio of 4:5 is 64:125.
Check the order of terms

The first term remains the numerator or first term after cubing, and the second term remains the second term.

Example: The triplicate ratio of 3:2 is 27:8, not 8:27.

Triplicate Ratio Concepts

Calculating the Triplicate Ratio

Cube both terms of the given ratio to obtain its triplicate ratio.

If the ratio is a:b, calculate a × a × a and b × b × b. The result is a³:b³. For example, for 3:4, 3³:4³ = 27:64.

Example: Given ratio = 5:2. Triplicate ratio = 5³:2³ = 125:8.

Triplicate Ratio After Simplification

The original ratio can be simplified before cubing because equivalent ratios have the same triplicate ratio.

If a:b = c:d, then a³:b³ = c³:d³. Therefore, simplify common factors first. For 8:12, division by 4 gives 2:3, so the triplicate ratio is 8:27.

Example: For 15:25, reduce by 5 to get 3:5. Its triplicate ratio is 27:125.

Finding the Original Ratio from a Triplicate Ratio

Take the cube roots of the two terms to recover the original ratio when both terms are perfect cubes.

If the triplicate ratio is A:B = a³:b³, then the original ratio is ∛A:∛B. The ratio should be simplified if the cube roots have a common factor.

Example: If the triplicate ratio is 64:125, the original ratio is ∛64:∛125 = 4:5.

Comparing a Ratio with Its Triplicate Ratio

The triplicate ratio is not found by multiplying both terms by 3; each term must be raised to the third power.

For a:b, multiplying both terms by 3 gives 3a:3b, which is equivalent to a:b. Triplication instead gives a³:b³. For example, the triplicate ratio of 2:5 is 8:125, not 6:15.

Example: Given 2:3, its equivalent ratio after multiplying by 3 is 6:9, but its triplicate ratio is 8:27.

Triplicate Ratio Video Lessons

Watch short topic-wise lessons for quick revision.

4 Lessons
Lesson 1 of 4 Quick Revision

Duplicate, Triplicate and Sub-Duplicate Ratios

Learn the definitions and application of duplicate, triplicate, and sub-duplicate ratios, with clear methods for understanding how these special ratios are formed and used.

Continue with more lessons and practice in PrepShots.Watch More in App - Start ₹1 Trial →
More Triplicate Ratio Lessons Scroll to explore →

Practice Triplicate Ratio Questions

Practise published questions related to this topic.

Triplicate Ratio Quick Quiz

Attempt 5 questions and check your score instantly.

Quick Revision Notes

Triplicate Ratio: Quick Revision

Use these rules to calculate and reverse triplicate ratios.

  • For a:b, the triplicate ratio is a³:b³.
  • Cube the two terms separately and preserve their order.
  • Simplify the given ratio before cubing to reduce calculation.
  • The triplicate ratio of 2:3 is 8:27.
  • To reverse a triplicate ratio A:B, take ∛A:∛B when the terms are perfect cubes.
  • Triplicate ratio means cubing the terms, not multiplying them by 3.

Triplicate Ratio FAQs

What is the triplicate ratio formula?

For a ratio a:b, the triplicate ratio is a³:b³. For example, the triplicate ratio of 2:5 is 8:125.

What is the triplicate ratio of 6:9?

First simplify 6:9 to 2:3. Its triplicate ratio is 2³:3³ = 8:27.

What is the triplicate ratio of 4:7?

Cube both terms: 4³:7³ = 64:343.

How is triplicate ratio different from multiplying a ratio by 3?

Triplicate ratio cubes each term. Thus, the triplicate ratio of 2:3 is 8:27, whereas multiplying both terms by 3 gives the equivalent ratio 6:9.

How do you find the original ratio from 27:64 as a triplicate ratio?

Take cube roots of both terms: ∛27:∛64 = 3:4. Therefore, the original ratio is 3:4.

What is the triplicate ratio of 10:15?

Simplify 10:15 to 2:3, then cube the terms. The triplicate ratio is 8:27.

Continue learning Triplicate Ratio on PrepShots

Continue on PrepShots