NCERT Solutions for class 7 maths Comparing

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%

 

  1. 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

 

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NCERT Solutions for class 7 maths Comparing Quantities                        EXERCISE -: 8.2 Q 1.  Convert the given fractional numbers to percent…