NCERT Solutions Class 7 Maths Chapter 8 Comparing Quantities Ex 8.1

NCERT Solutions Class 7 Mathematics 
Chapter – 8 (Comparing Quantities)

The NCERT Solutions in English Language for Class 7 Mathematics Chapter – 8 Comparing Quantities Exercise 8.1 has been provided here to help the students in solving the questions from this exercise. 

Chapter : 8 Comparing Quantities

• NCERT Solution Class 7 Maths Exercise – 8.2
• NCERT Solution Class 7 Maths Exercise – 8.3

Exercise – 8.1 

1. Find the ratio of:
(a) ₹ 5 to 50 paise
(b) 15 kg to 210 g
(c) 9 m to 27 cm
(d) 30 days to 36 hours

Solution –

(a) ₹ 5 to 50 paise
We know that,
₹ 1 = 100 paise
Then,
₹ 5 = 5 × 100 = 500 paise
Now we have to find the ratio,
⇒ =
So, the required ratio is 10 : 1.

(b) 15 kg to 210 g
We know that,
1 kg = 1000 g
Then,
15 kg = 15 × 1000 = 15000 g
Now we have to find the ratio,
⇒ =

⇒   ——- [∵ divide both by 3]
So, the required ratio is 500 : 7.

(c) 9 m to 27 cm
We know that,
1 m = 100 cm
Then,
⇒ 9 m = 9 × 100 = 900 cm
Now we have to find the ratio,
⇒ = ——–  [∵ divide both by 9]
So, the required ratio is 100 : 3.

(d) 30 days to 36 hours
We know that,
1 day = 24 hours
Then,
30 days = 30 × 24 = 720 hours
Now we have to find the ratio,
⇒ =     ———— [∵ divide both by 36]
So, the required ratio is 20 : 1.

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

Solution –
Using Unitary Method, we have
6 students require 3 computers
∴ 1 student will require = computers
∴ 24 students will require =  x 24 computers
⇒ 3 × 4 computers
⇒ 12 computers
Hence the number of computers required = 12.

3. Population of Rajasthan = 570 lakhs and population of UP = 1660 lakhs. Area of Rajasthan = 3 lakh km² and area of UP = 2 lakh km².
(i) How many people are there per km² in both these States?
(ii) Which State is less populated?

Solution –
(i) How many people are there per km² in both these States?
Population of Rajasthan = 570 lakh
Area of Rajasthan = 3 lakh Km²
Then, population of Rajasthan in 1 km² area = = 190 people per km²
Population of UP = 1660 Lakh
Area of UP = 2 Lakh km²
Then, population of UP in 1 lakh km² area = = 830 people per km²

(ii) Which State is less populated?
Rajasthan is less populated state.