Comapring Quantities Class 7 NCERT Concept & Practice Questions

Have you ever wondered how discounts in shopping, interest in banks, or even exam scores are compared? Imagine getting 20% off on your favorite dress or scoring 80 out of 100 in a test. These are all examples of comparing quantities in real life.

In Class 7 Maths, Comparing Quantities helps you understand how numbers relate to each other using ratios, percentages, profit and loss, and simple interest. Once you learn this chapter, you will start noticing maths everywhere around you.

Let’s break it down in a simple and fun way so that it becomes easy to understand and remember.

What Does Comparing Quantities Mean

Comparing quantities means finding out how one quantity is related to another. Instead of just looking at numbers, we express their relationship using ratios, fractions, or percentages.

For example

• If one student scores 80 marks and another scores 40 marks, we can say the first student scored twice as much.
• If a shirt costs 500 and you get it for 400, you compare the original and discounted price.

So, comparing quantities helps us answer questions like

• How much more
• How much less
• What part or percentage

Ratio and Its Role in Comparison

A ratio compares two quantities by division. It tells us how many times one quantity is of another.

Example

If there are 10 boys and 5 girls in a class
Ratio of boys to girls = 10 : 5 = 2 : 1

This means there are twice as many boys as girls.

Important Points

• Ratios should be in simplest form
• Both quantities must have the same unit

Practice Question

Find the ratio of 50 cm to 1 m

Solution
1 m = 100 cm
Ratio = 50 : 100 = 1 : 2

Understanding Percentages in Daily Life

Percentage means per hundred. It is one of the most common ways to compare quantities.

Formula

Percentage = (Part ÷ Whole) × 100

Examples

• 50% means 50 out of 100
• 25% means 25 out of 100

Conversion Table

Example Question

Convert 3/5 into percentage

Solution
(3 ÷ 5) × 100 = 60%

Finding Increase and Decrease Percentage

Sometimes quantities increase or decrease, like prices or marks. We express this change in percentage.

Formula

Percentage Increase = (Increase ÷ Original Value) × 100
Percentage Decrease = (Decrease ÷ Original Value) × 100

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Example

Price of a book increases from 200 to 250

Increase = 50
Percentage increase = (50 ÷ 200) × 100 = 25%

Profit and Loss Made Easy

When you buy and sell things, you either make a profit or incur a loss.

Key Terms

• Cost Price means price at which you buy
• Selling Price means price at which you sell

Formulas

Profit = Selling Price − Cost Price
Loss = Cost Price − Selling Price

Profit % = (Profit ÷ Cost Price) × 100
Loss % = (Loss ÷ Cost Price) × 100

Example

A toy is bought for 100 and sold for 120

Profit = 20
Profit % = (20 ÷ 100) × 100 = 20%

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Discount and Marked Price

When you go shopping, you often see discounts. This is another real life example of comparing quantities.

Terms

• Marked Price is the original price
• Discount is the reduction in price

Formula

Discount = Marked Price − Selling Price
Discount % = (Discount ÷ Marked Price) × 100

Example

Marked price = 1000
Discount = 200

Discount % = (200 ÷ 1000) × 100 = 20%

Quick Table

Simple Interest Explained

Banks give interest when you deposit money. This is called simple interest.

Formula

Simple Interest = (Principal × Rate × Time) ÷ 100

Where

• Principal is the original amount
• Rate is interest rate
• Time is in years

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Example

Principal = 1000
Rate = 5%
Time = 2 years

SI = (1000 × 5 × 2) ÷ 100 = 100

Total Amount = 1000 + 100 = 1100

Real Life Applications of Comparing Quantities

This chapter is not just about solving questions. It helps you in daily life situations.

Where You Use It

• Shopping discounts
• Bank interest
• Exam results
• Comparing prices
• Business profit and loss

Example

If two shops offer discounts of 10% and 20%, you can quickly decide which is better.

Practice Questions for Better Understanding

Basic Level

1. Convert 1/4 into percentage
2. Find 20% of 500
3. Write ratio of 15 to 45

Intermediate Level

4. A shirt costs 800. Discount is 10%. Find selling price
5. Find profit percentage if CP = 200 and SP = 250

Advanced Level

6. Find simple interest on 2000 at 5% for 3 years
7. Price of an item increases from 400 to 500. Find percentage increase

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Common Mistakes Students Make in Comparing Quantities

Even though Comparing Quantities looks easy, many students lose marks due to small mistakes. Understanding these can help you avoid them and improve accuracy.

Mixing Units

One of the most common mistakes is comparing quantities with different units.
For example, comparing 1 m with 50 cm directly is incorrect. Always convert them into the same unit first.

Forgetting to Multiply by 100

While calculating percentage, students often forget to multiply by 100.
This leads to wrong answers even if the calculation is correct.

Confusing Profit and Loss Formulas

Students sometimes mix up Cost Price and Selling Price.
Always remember:

• Profit happens when SP is more than CP
• Loss happens when CP is more than SP

Not Reading the Question Properly

Many errors happen because students rush through questions.
Words like increase, decrease, discount, or interest give important clues.

Tip for Students

Practice step by step solving and double check formulas before final answers. This simple habit can improve your scores a lot.

Tips to Master Comparing Quantities Easily

If you want to score well in this chapter, consistency and smart learning matter more than memorizing formulas.

Understand Before You Memorize

Instead of mugging up formulas, try to understand what they mean.
For example, percentage is simply “out of 100”.

Practice Daily with Real Life Examples

Look around you

• Discounts in stores
• Scores in exams
• Bank interest

Relating maths to real life makes it easier to remember.

Use Tables and Short Tricks

Revise Formulas Regularly

Spend 5 minutes daily revising formulas. This helps in quick recall during exams.

Solve NCERT Questions First

NCERT questions are the base. Once you are confident, move to extra questions.

Why Choose PlanetSpark for Class 7 Maths Learning

At PlanetSpark, learning maths is not just about solving problems but building confidence and clarity.

Students get

• Personalized attention from expert teachers
• Interactive sessions that make maths fun and easy
• Real life examples to understand concepts better
• Regular practice and doubt solving
• Instant doubt solving during and after sessions
• Continuous performance tracking and feedback for improvement
• Fun quizzes and activities to make learning enjoyable
• Focus on building problem solving and logical thinking skills
• Flexible class timings that fit your child’s schedule

Conclusion

Comparing quantities is one of the most practical chapters in Class 7 Maths. From percentages to profit and loss, and from discounts to interest, these concepts are used almost everywhere in daily life.

Once you understand the formulas and practice regularly, this chapter becomes very easy and even fun. So next time you see a sale sign or calculate your marks, remember you are already using maths in real life.