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Proportional Reasoning-1

CBSE · Class 8 · Mathematics

Flashcards for Proportional Reasoning-1 — CBSE Class 8 Mathematics. Quick Q&A cards covering key concepts, definitions, and formulas.

45 questions22 flashcards5 concepts
22 Flashcards
Card 1Basic Concepts

What is a ratio and how is it written?

Answer

A ratio is a comparison of two quantities using division. It is written as a:b, where 'a' and 'b' are called the terms of the ratio. For example, if there are 60 mm width and 40 mm height, the ratio i

Card 2Basic Concepts

What does the ratio 5:3 mean?

Answer

The ratio 5:3 means that for every 5 units of the first quantity, there are 3 units of the second quantity. For example, if boys to girls ratio is 5:3, then for every 5 boys, there are 3 girls.

Card 3Simplifying Ratios

How do you find the simplest form of a ratio?

Answer

To find the simplest form of a ratio, divide both terms by their HCF (Highest Common Factor). For example, 60:40 has HCF = 20, so dividing both terms: 60÷20 : 40÷20 = 3:2.

Card 4Proportions

When are two ratios said to be proportional?

Answer

Two ratios are proportional when they are equal in their simplest forms. We use the symbol '::' to show proportion. For example, 6:4 :: 9:6 because both simplify to 3:2.

Card 5Cross Multiplication

What is cross multiplication and when is it used?

Answer

Cross multiplication is used to check if two ratios are proportional or to find missing terms. If a:b :: c:d, then a×d = b×c. For example, in 3:4 :: 6:8, we get 3×8 = 4×6 = 24.

Card 6Problem Solving

Solve: 12:15 :: 8:?

Answer

Using cross multiplication: 12 × ? = 15 × 8 12 × ? = 120 ? = 120 ÷ 12 = 10 Therefore, 12:15 :: 8:10

Card 7Rule of Three

What is the Rule of Three (Trairasika)?

Answer

The Rule of Three is an ancient method to solve proportion problems with four quantities where three are known and one is unknown. If a:b :: c:d, then d = (b×c)/a. This method was used by ancient Indi

Card 8Problem Solving

A car travels 120 km in 2 hours. How far will it travel in 5 hours at the same speed?

Answer

Set up proportion: 120:2 :: ?:5 Using cross multiplication: 2 × ? = 120 × 5 2 × ? = 600 ? = 300 km The car will travel 300 km in 5 hours.

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Frequently Asked Questions

What are the important topics in Proportional Reasoning-1 for CBSE Class 8 Mathematics?

Proportional Reasoning-1 covers several key topics that are frequently asked in CBSE Class 8 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.

Start by understanding all key concepts. Practise previous year questions from this chapter. Revise formulas and definitions regularly. Use flashcards for quick revision before the exam.

There are 22 flashcards for Proportional Reasoning-1 covering key definitions, formulas, and concepts. Use them daily for 10–15 minutes for best results.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.