NCERT Solutions Class 8 Mathematics
Chapter – 8 (Comparing Quantities)
The NCERT Solutions in English Language for Class 8 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
Exercise – 8.1
1. Find the ratio of the following:
(a) Speed of a cycle 15 km per hour to the speed of a scooter 30 km per hour.
(b) 5 m to 10 km
(c) 50 paise to ₹5
Solution –
(a) Speed of a cycle = 15 km/hr
Speed of a scooter = 30 km/hr
Speed of cycle : Speed of scooter =
Thus, the ratio is 1 : 2
(b) Since 1 km = 1000 m
Therefore, 10 km = 10 × 1000 = 10000 m
5 m to 10 km = 5 m to 10000 m =
Thus, the ratio is 1 : 2000
(c) Since, ₹1 = 100 paise
₹ 5 = 5 × 100 paise = 500 paise
50 paise to Rs 5 = 50 paise to 500 paise =
Thus, the ratio is 1 : 10
2. Convert the following ratio to percentages:
(a) 3 : 4 (b) 2 : 3
Solution –
(a) 3 : 4
= =
× 100% = 75%
(b) 2 : 3
= =
x 100% =
=
3. 72% of 25 students are good in mathematics. How many are not good in mathematics?
Solution – Total number of students = 25
Students good in mathematics = 72%
∴ Students who are not good in mathematics = (100 – 72) % = 28%
∴ Number of those students who are not good in mathematics = 28% of 25
= = 7
Therefore, 7 students are not good in mathematics.
4. A football team won 10 matches out of the total number of matches they played. If their win percentage was 40, then how many matches did they play in all?
Solution – Let the total number of matches played by the team be x.
Given that the team won 10 matches and the winning percentage of the team was 40%.
⇒ × x = 10
40 x = 10 × 100
40 x = 1000
x = = 25
Therefore, the team played 25 matches.
5. If Chameli had ₹600 left after spending 75% of her money, how much did she have in the beginning?
Solution – Let the amount of money which Chameli had, in the beginning, be x
Given that, after spending 75% of ₹x, she was left with ₹600
So, (100 – 75)% of x = ₹600
Or, 25% of x = ₹600
× x = ₹600
x = ₹600
x = ₹600 × 4
= ₹2400
Therefore, Chameli had ₹2400 in the beginning.
6. If 60% of people in the city like cricket, 30% like football and the remaining like other games, then what per cent of the people like other games? If the total number of people is 50 lakhs, find the exact number who like each type of game.
Solution – Percentage of people who like other games = (100 – 60 – 30)%
= (100 – 90)%
= 10%
Total number of people = 50 lakhs
So,
Number of people who like cricket = x 50 = 30 lakhs
Number of people who like football = x 50 = 15 lakhs
Number of people who like other games = x 50 = 5 lakhs
