8th Maths 8.1

Chapter 8

Comparing Quantities

NCERT Class 8th Solution of Exercies 8.2

NCERT Class 8th Solution of Exercies 8.3

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) 5m to 10 km
c) 50 paise to ₹ 5

`text{Solution:}`

a) `text{ Speed of a cycle: speed of a scooter}`

`=15:30`

`=15/30`

`=1/2`

`=1:2`

`text{Answer:}`

`=1:2`

b) `text{5m:10 km}`

`=text{5m:10}times1000text{m}``[text{1km=1000m}]`

`=5:10000`

`=1:2000`

`text{Answer:}`

`=1:2000`

c) `text{50 paise:₹5}`

`=text{50paise:5}times100text{paise}``[text{₹1=100paise}]`

`=50:500`

`=1:10`

`text{Answer:}`

`=1:10`

2. Convert the following ratios to percentages. 

a) 3:4 

b) 2:3

`text{Solution:}`

a) `3:4`

`=3/4times100`

`=3times25`

`=75%`

`text{Answer:}`

`=75%`

b) `2:3`

`=2/3times100`

`=200/3`

`=66 2/3%`

`text{Answer:}`

`=66 2/3%`

3. 72% of 25 students are interested in mathematics. How many are not interested in mathematics?

`text{Solution:}`

`text{Number of students are not interested in}``text{ mathematics}`

`text{=Total% - Number of students are interested}``text{ in mathematics}`

`=100-72`

`=28%`

`text{or}`

`text{Number of students are interested in}``text{ mathematics}`

`=72/100times25`

`=72/4`

`=18`

`text{Number of students are not interested in}``text{ mathematics}`

`=25-18`

`=7`

`text{Answer:}`

`text{7 students are not interested 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?

`text{Solution:}`

`text{Win % of total matches is 10}`

`40/100times text{total matches}=10`

`2/5times text{total matches}=10`

`text{total matches}=10times5/2`

`text{total matches}=25`

`text{Answer:}`

`text{They play 25 matches}.`

5. If Chameli had ₹ 600 left after spending 75% of her money, how much did she have
in the beginning?

`text{Solution:}`

`text{total % - spend % = Left %}`

`100-75=25%`

`25/100times text{total money}=600`

`1/4times text{total money}=600`

`text{total money}=600times4`

`text{total money}=2400`

`text{Answer:}`

`text{She has ₹ 2400 in the beginning.}`

6. If 60% of people in a city like a cricket, 30% like football, and the remaining like other games, then what percent of the people like other games? If the total number of people is 50 lakh, find the exact number who like each type of game.

`text{Solution:}`

`text{People like a cricket}`

`=60/100times50text{ lakh}`

`=6/10times50text{ lakh}`

`=6times5text{ lakh}`

`=30text{ lakh}`

`text{People like a football}`

`=30/100times50text{ lakh}`

`=3/10times50text{ lakh}`

`=3times5text{ lakh}`

`=15text{ lakh}`

`text{People like other games}`

`text{other games = 50-(30+15)=5 lakh}`

`text{Answer:}`

`text{Cricket 30 lakh, Football 15 lakh,}``text{ and other games 5 lakh.}`