NCERT Solutions for class 7 maths Comparing Quantities
EXERCISE -: 8.2
Q 1. Convert the given fractional numbers to percent .
- 1/8
In order to converts a fractional into a percentage multiply the fraction by 100 and put the percent sign %
= (1/8) X 100 %
= 100/8%
= 12.5%
- 5/4
= (5/4) X 100 %
= 500/4%
= 125%
- 3/40
= (3/40) X 100%
= 300/40%
= 30/4%
= 7.5%
- 2/7
= (2/7) x 100%
= 200/7%
= 284/7 %
Q2. Convert the given decimal fractions to percent .
- 65
65/100
= (65/100) x 100
= 65%
- 1
= 21/10
= (21/10) x 100
= 210%
© 0.02
= 2/100
= (2/100) x 100
= 2%
- 35
= 1235/100
= (1235/100)x100)
= 1235%
Q3. Estimate what a part of the figures is coloured and hence find the percent which is coloured.
Solution :-
By observing the given figures ,
We can able to identify that 1 part is shaded out of 4 equal parts
It is represented by the fraction = 1/4
Then,
= 1/4 x 100
= 100/4
= 25%
Hence , 25% of the figure is coloured.
(ii)
Solution:-
By observing the given figures,
We can able to identify that 3 part is shaded out of 5 equal parts .
It is represented by a fraction = 3/5
Then,
= (3/5) x 100
= 300/5
= 60%
Hence , 60% of figures is coloured
(iii)
Solution:-
By observing the given figures,
We can able to identify that 3 parts is shaded out of 8 equal parts.
It is represented by a fraction = 3/8
Then,
= (3/8) x 100
= 300/8
= 37.5%
Hence , 37.5% of figures is coloured.
Q4. Find:
- 15% of 250
Solution:-
We have,
= (15/100) x 250
=(15/10)x 25
= (15/2) x 5
= (75/2)
= 37.5
- 1% of 1 hour
Solution:-
= (1/100) x 3600
= 1×36
= 36 seconds
(C) 20% of Rs 2500
Solution:-
= (20/100) x 2500
= 20 x 25
= Rs 500
(D) 75% Of 1 kg
Solution:-
=(75/100)X100O
=75X10
=750g
Q5. Find the whole quantity if
- 5% Of it is 600
Solution:-
Let us assume the whole quantity be x,
Then,
(5/100) x (x) =600
X=600 x (100/5)
X=60000/5
X=12000
- 12 % Of it is Rs.1080
Solution:-
Let us assume the whole quantity be x ,
Then,
(12/100) x (x) =1080
X=1080 x (100/12)
X=540 x (100/6)
X=90 x 100
X=rs 9000
- 40% of it is 500 km
Solution:-
(40/100) x (x)=500
X=500 x (100/40)
X=500 (10/4)
X=500 x 2.5
X=1250 km
- 70% of it is 14 min
Solution :-
(70/100) x (x)=14
X= 14 x (100/70)
X= 14 x (10/7)
X= 20min.
- 8% of it is 40 ltr
Solution:-
(8/100) x (x)=40
X=40 x (100/8)
X=40 x (100/8)
X=40 x 12.5
X=500 ltr
Q6. Convert given percent to decimal fractions and also fractions in simplest form:
- 25%
= (25/100)
= 1/4
= 0.25
- 150%
= (150/100)
= 3/2
= 1.5
© 20%
= (20/100)
= 1/5
= 0.2
(d) 5%
= (5/100)
= 1/20
= 0.05
Q7. In a city, 30% are females , 405 are males and remaining are children . What percent are children ?
Solution:-
From the question , it is given that
Percentage of female in a city = 30%
Percentage of males in a city = 40%
Total percentage of males and females both = 70%
Now we have to find the percentage of children = 100-70
= 30%
So, 30% are children.
Q8. Out of 15000 voters in a constituency , 60% voted. Find the percentage of the voters who did not vote can you now find how many actually did not vote ?
Solution:-
Total no of voters in the constituency = 15000
Percentage of the people who did not voted in elections = 100-60 = 40%
Total no of voters who did not voted in the elections = 40% of 15000
= (40/100) x 15000
= 0.4 x 15000
= 6000 voters
Q9. Meeta saves Rs 4000 from her salary. If this is 10% of her salary. What is her salary ?
Solution:-
Let us assume meeta salary be Rs x
Then,
10% of Rs x = Rs 4000
(10/100) x (x) = 4000
X = 4000 x (100/10)
X = 4000 x 10
X = Rs 40000
Q10. A local cricket team played 20 matches in one season. It won 25% of them . How many matches did they win?
Solution:-
Total matches played by a local team = 20
Percentage of matches won by the local team = 25%
Then,
Number of matches won by the team = 25% of 20
= (25/100) x 20
= 25/5
= 5 matches