NCERT Solutions for Class 8 Maths Chapter 7 Exercise 7.1
NCERT Solutions for Class 8 Maths Chapter 7 – Comparing Quantities Ex 7.1 are given here in simple, step-by-step form. NCERT stands for National Council of Educational Research and Training, the body that makes your textbook. This chapter helps you compare two amounts using ratios and percentages. A ratio tells you how many times one amount is of another. A percentage is a way of showing a part out of one hundred. We write per cent with the sign %. So x% means x out of 100.
This exercise has 6 questions. They come from daily life, such as a ratio of speeds, sharing a sum of money, the number of boys and girls in a class, prices of a TV and a washing machine, and people watching different channels on TV. Students can use this page for homework and revision, parents can use it to check the work at home, and teachers can use it in class. A free printable PDF of these solutions is also available for offline study.
NCERT Solutions for Class 8 Maths Chapter 7 Exercise 7.1 (Comparing Quantities)
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Exercise 7.1 – Questions and Answers
Class 8 Maths Chapter 7 – Comparing Quantities, Exercise 7.1
Q 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
Answer:
(a) Ratio of the speed of cycle to the speed of scooter = 15/30 = 1 : 2
(b) Since 1 km = 1000 m,
∴ Required ratio = 5 m / 10 km = 5 m / (10 × 1000 m) = 1 : 2000
(c) Since ₹ 1 = 100 paise,
∴ Required ratio = 50 paise / ₹ 5 = 50 paise / 500 paise = 1 : 10
Q 2. Convert the following ratios to percentages.
(a) 3 : 4
(b) 2 : 3
Answer:
(a) 3 : 4 = 3/4 = 3/4 × 100/100 = 3/4 × 100% = 75%
(b) 2 : 3 = 2/3 = 2/3 × 100/100 = 2/3 × 100% = 200/3 % = 66⅔ %
Q 3. 72% of 25 students are good in mathematics. How many are not good in mathematics?
Answer:
Given that 72% of 25 students are good in mathematics.
Therefore, percentage of students who are not good in mathematics
= (100 − 72)% = 28%
Thus, the number of students who are not good in mathematics
= 28/100 × 25 = 7
Hence, 7 students are not good in mathematics.
Q 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?
Answer:
Let the total number of matches played by the team be x.
It is given that the team won 10 matches and the winning percentage of the team was 40%.
Therefore,
40/100 × x = 10
⇒ x = 10 × 100/40
⇒ x = 25
Hence, the team played 25 matches in all.
Q 5. If Chameli had ₹ 600 left after spending 75% of her money, how much did she have in the beginning?
Answer:
Let the amount of money which Chameli had in the beginning be x.
It is given that after spending 75% of ₹ x, she was left with ₹ 600.
Therefore, (100 − 75)% of x = ₹ 600
⇒ 25% of x = ₹ 600
⇒ 25/100 × x = ₹ 600
⇒ x = ₹ (600 × 100/25) = ₹ 2400
Hence, she had ₹ 2400 in the beginning.
Q 6. If 60% people in a 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 are 50 lakh, find the exact number who like each type of game.
Answer:
Percentage of people who like other games = (100 − 60 − 30)%
= (100 − 90)%
= 10%
It is given that the total number of people = 50 lakh
- Number of people who like cricket = (60/100 × 50) lakh = 30 lakh
- Number of people who like football = (30/100 × 50) lakh = 15 lakh
- Number of people who like other games = (10/100 × 50) lakh = 5 lakh
Related Links
- NCERT Solutions Class 8 Maths Chapter 7 Exercise 7.2
- NCERT Solutions Class 8 Maths Chapter 7 Exercise 7.3