NCERT Class 7 Maths Chapter 8 Comparing Quantities Exercise 8.1

Chapter 8 Comparing Quantities Exercise 8.1

Question 1: Find the ratio of:
(a) ₹ 5 to 50 paise
Answer:
(₹ 1 = 100 paise)
₹ 5 = 5 × 100 = 500 paise
= 500/50
= 10/1
= 10:1

(b) 15 kg to 210 g
Answer:
1 kg = 1000 g
15 kg = 15 × 1000 = 15000 g
= 15000/210
= 1500/21
= 500:7

(c) 9 m to 27 cm
Answer:
1 m = 100 cm
9 m = 9 × 100 = 900 cm
= 900/27
= 100/3
= 100:3

(d) 30 days to 36 hours
Answer:
1 day = 24 hours
30 days = 30 × 24 = 720 hours
= 720/36
= 20/1
= 20:1

Question 2: In a computer lab, there are 3 computers for every 6 students. How many computers will be needed for 24 students?
Answer:
Number of computer required for 6 students = 3
Number of computer required for 1 student = 3/6
= 1/2
Number of computer required for 24 students = 24 × 1/2
= 24/2
= 12
Therefore, number of computer required for 24 students is 12 computers.

Question 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?
Answer:
(i) Population of Rajasthan = 570 lakh
    Area of Rajasthan = 3 lakh km2
Population of Rajasthan in 1 km2 area = 570 lakh/3 lakh km2
= 190 people per km2
    Population of UP = 1660 Lakh
    Area of UP = 2 Lakh km2
Population of UP in 1 lakh km2 area = 1660 lakh/2 lakh km2
= 830 people per km2

(ii) Rajasthan is the less populated state.