Contents

NCERT Solutions for Class 7 Maths Chapter 8 Comparing Quantities are part of NCERT Solutions for Class 7 Maths. Here we have given NCERT Solutions for Class 7 Maths Chapter 8 Comparing Quantities.

Board |
CBSE |

Textbook |
NCERT |

Class |
Class 7 |

Subject |
Maths |

Chapter |
Chapter 8 |

Chapter Name |
Comparing Quantities |

Exercise |
Ex 8.1, Ex 8.2, Ex 8.3. |

Number of Questions Solved |
14 |

Category |
NCERT Solutions |

## NCERT Solutions for Class 7 Maths Chapter 8 Comparing Quantities

### Chapter 8 Comparing Quantities Exercise 8.1

**Ex 8.1 Class 7 Maths Question 1.**

Find the ratio of:

**(a)** ₹5 to 50 paise

**(b)** 15 kg to 210 kg

**(c)** 9 m to 27 cm

**(d)** 30 days to 36 hours

**Solution:
**

**Ex 8.1 Class 7 Maths Question 2.**

In a computer lab, there are 3 computers for every 6 students. How many computers are needed for 24 students?

**Solution:**

∵ For every 6 students, there are 3 computers

∴ For 1 student there are \(\frac { 3 }{ 6 } \) computer

∴ For 24 students there are \(\frac { 3 }{ 6 } \) × 24 computers = 12 computers

Hence, 12 computers are needed for 24 students.

**Ex 8.1 Class 7 Maths Question 3.**

Population of Rajasthan = 570 lakhs and population of U.P. = 1660lakhs. Area of Rajasthan = 3 lakh km2 and area of U.P. = 2 lakh km^{2}.

**(i)** How many people are there per km^{2} in both these states?

**(ii)** Which state is less populated?

**Solution:
**

### Chapter 8 Comparing Quantities Exercise 8.2

**Ex 8.2 Class 7 Maths Question 1.**

Convert the given fractional number to per cents :

**(a)** \(\frac { 1 }{ 8 } \)

**(b)** \(\frac { 5 }{ 4 } \)

**(c)** \(\frac { 3 }{ 40 } \)

**(d)** \(\frac { 2 }{ 7 } \)

**Solution:
**

**Ex 8.2 Class 7 Maths Question 2.**

Convert the given decimal fractions to per cents.

**(a)** 0.65

**(b)** 2.1

**(c)** 0.02

**(d)** 12.35

**Solution:
**

**Ex 8.2 Class 7 Maths Question 3.**

Estimate what part of the figures is coloured and hence find the per cent which is coloured.

**Solution:
**

**Ex 8.2 Class 7 Maths Question 4.**

Find :

**(a)** 15% of 250

**(b)** 1% of 1 hour

**(c)** 20% of ₹ 2500

**(d)** 75% of 1 kg

**Solution:
**

**Ex 8.2 Class 7 Maths Question 5.**

Find the whole quantity if

**(a)** 5% of it is 600

**(b)** 12% of it is ? 1080

**(c)** 40% of it is 500 km

**(d)** 70% of it is 14 minutes

**(e)** 8% of it is 40 litres

**Solution:
**

**Ex 8.2 Class 7 Maths Question 6.**

Convert given per cents to decimal fractions and also to fractions in simplest forms :

**(a)** 25%

**(b)** 150%

**(c)** 20%

**(d)** 5%

**Solution:
**

**Ex 8.2 Class 7 Maths Question 7.**

In a city, 30% are females, 40% are males and remaining are children. What per cent are children?

**Solution:**

In a city,

Percentage of females = 30%

Percentage of males = 40%

Percentage of children = (100 – 30 – 40)% = 30%

**Ex 8.2 Class 7 Maths Question 8.**

Out of 15,000 voters in a constituency, 60% voted. Find the percentage of voters who did not vote. Can you now find how many actually did not vote?

**Solution:**

Percentage of voters who voted = 60%

Percentage of voters who did not vote = (100 – 60)% = 40%

Total number of voters = 15000

Number of voters who did not vote

= 40% of 15000

= ( \(\frac { 40 }{ 100 } \) × 15000 ) = 6000

**Ex 8.2 Class 7 Maths Question 9.**

Meeta saves ₹ 400 from her salary. If this is 10% of her salary, what is her salary?

**Solution:
**

**Ex 8.2 Class 7 Maths Question 10.**

A local cricket team played 20 matches in one season. It won 25% of them. How many matches did they win?

**Solution:**

Out of 100, 25% matches are won. Then, out of 20, the number of matches that the team won

= \(\frac { 25 }{ 100 } \) × 20 = \(\frac { 1 }{ 4 } \) × 20 = 5

### Chapter 8 Comparing Quantities Exercise 8.3

**Ex 8.3 Class 7 Maths Question 1.**

Tell what is the profit or loss in the following transactions. Also find profit per cent or loss per cent in each case.

**(a)** Gardening shears bought for ₹ 250 and sold for ₹ 325.

**(b)** A refrigerator bought for ₹ 12,000 and sold at ₹ 13,500.

**(c)** A cupboard bought for ₹ 2,500 and sold at ₹ 3,000.

**(d)** A skirt bought for ₹ 250 and sold at ₹ 150.

**Solution:
**

**Ex 8.3 Class 7 Maths Question 2.**

Convert each part of the ratio to percentage :

**(a)** 3 : 1

**(b)** 2 : 3 : 5

**(c)** 1 : 4

**(d)** 1 : 2 : 5

**Solution:
**

**Ex 8.3 Class 7 Maths Question 3.**

The population of a city decreased from 25,000 to 24,500. Find the percentage decrease.

**Solution:**

Original population of the city = 25000

Decreased population of the city = 24500

∴ Decrease in population = 25000 – 24500 = 500

∴ Percentage of decrease = ( \(\frac { 500 }{ 25000 } \) × 100 ) % = 2%

**Ex 8.3 Class 7 Maths Question 4.**

Arun bought a car for ₹ 3,50,000. The next year, the price went upto ₹ 3,70,000. What was the percentage of price increase?

**Solution:**

Original cost of the car = ₹ 3,50,000

Increased cost of the car = ₹ 3,70,000

∴ Increase in price = ₹ (370000 – 350000)

= ₹ 20,000

∴ Percentage increase = ( \(\frac { 20000 }{ 350000 } \) × 100 )% = \(\frac { 40 }{ 7 } \) % = 5 \(\frac { 5 }{ 7 } \)%

**Ex 8.3 Class 7 Maths Question 5.**

I buy a T.V. for ₹ 10,000 and sell it at a profit of 20%. How much money do I get for it?

**Solution:
**

**Ex 8.3 Class 7 Maths Question 6.**

Juhi sells a washing machine for ? 13,500. She loses 20% in the bargain. What was the price at which she bought it?

**Solution:**

We have, S.P. = ₹13,500 and loss = 20%.

**Ex 8.3 Class 7 Maths Question 7.**

**(i)** Chalk contains calcium, carbon and oxygen in the ratio 10:3:12. Find the percentage of carbon in chalk.

**(ii)** If in a stick of chalk, carbon in 3g, what is the weight of the chalk stick?

**Solution:
**

**Ex 8.3 Class 7 Maths Question 8.**

Amina buys a book for ₹ 275 and sells it at a loss of 15%. How much does she sell it for?

**Solution:
**

**Ex 8.3 Class 7 Maths Question 9.**

Find the amount to be paid at the end of 3 years in each case :

**(a)** Principal = ₹ 1,200 at 12% p.a.

**(b)** Principal = ₹ 7,500 at 5% p.a.

**Solution:
**

**Ex 8.3 Class 7 Maths Question 10.**

What rate gives ₹ 280 as interest on a sum of ₹ 56,000 in 2 years?

**Solution:
**

**Ex 8.3 Class 7 Maths Question 11.**

If Meena gives an interest of ₹ 45 for one year at 9% rate p.a. What is the sum she has borrowed?

**Solution:
**

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