SChand Composite Mathematics Class 7 Chapter 9 Percentage and it's application Exercise 9A

  Exercise 9A

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Q1 | Ex-9A | Class 7 | SChand Composite Maths | Percentage and it's application | myhelper

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Question 1 

Name each of fraction as percent: 

(i) $\frac{3}{100}$

Sol: 3%

(ii) $\frac{29}{100}$

Sol: 29% 

(iii)  $\frac{151}{100}$

Sol: 151%

(iv)  $\frac{12.5}{100}$ 

Sol: $=12.5 \%$

(v) $\frac{235}{100}$ 

Sol: 235% 

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Question 2

Express each of the following as a fraction in Simplest form: 

(i) $25 \%$ 

Sol: $\frac{25}{100}=\frac{1}{4}$

(ii) 625% 

Sol: $\frac{625}{100}$

$\frac{25}{4} \Rightarrow 6 \frac{1}{4}$

(iii) $33 \frac{1}{2} \%$

Sol: $=\frac{67}{2} \%=\frac{67}{200}$

(iv) $66 \frac{2}{3} \%$

Sol: $\frac{200}{3} \%=\frac{200}{300}=\frac{2}{3}$

 

(v) 9.2% 

Sol: $\frac{9 \cdot 2}{1000}=\frac{23}{250}$

(vi) 18.75 % 

Sol: $\frac{18.75}{100}$

=$\frac{1875}{100 \times 100}$

=$\frac{3}{16}$

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Question 3

Convert each of the following Percent into decimal: 

(i) 27% 

Sol: $\frac{27}{100}=0.27$

(ii) 8%

Sol:  $\frac{8}{100}=0.08$

(iii) 130%

Sol: $\frac{130}{100}=1.3$

(iv) 69% 

Sol: $\frac{69.5}{100}=0.695$ 

(v) $3.68 \%$

Sol: $\frac{3.68}{100}=0.0368$

(vi) $0.0208 \%$

Sol: $\frac{0.0208}{100}=0.000208$

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Q4 | Ex-9A | Class 7 | SChand Composite Maths | Percentage and it's application | myhelper

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Question 4

Express the following fractions as Percent:

(i)  $\frac{1}{2} \times 100$

Sol: 50%

= $\frac{50}{100}=\frac{1}{2}$

(ii) $\frac{17}{25} \times 100$

Sol: 68% 

(iii) $\frac{3}{8} \times 100$

Sol: $\frac{75}{2}=37.5 \%$

(iv) $2 \frac{7}{16}$

Sol: $\frac{39}{16} \times 100$

$\frac{975}{4}=243.75 \%$

(v) $\frac{14}{75}=\times 100$

Sol: $\frac{56}{3}=18 \frac{2}{3} \%$

(vi) $\frac{2}{3}$

Sol: $\frac{2}{3}\times  100$

=$66 \frac{2}{3}$%

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Q5 | Ex-9A | Class 7 | SChand Composite Maths | Percentage and it's application | myhelper

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Question 5

Convert the following decimals into percent: 

(i) $0.58 \times 100$

Sol: 5.8%

(ii) $0.6 \times 100$

Sol: 60%

(iii) $0.039 \times 100$

Sol: 3.9%

(iv) 0.708 $\times 100$

Sol: 70.8%

(v) $2.05 \times 100$

Sol: = 205%

(vi) $0.001 \times 100$

Sol: 0.1%

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Question 6

Find the value of: 

(i)  $20 \%$ of 650

Sol: $\frac{26}{100} \times 650$

=130 answer 

(ii) $140 \%$ of 75

Sol: $\frac{140}{100} \times 75$

$\Rightarrow 35 \times 3$

$=105 \mathrm{Ans}$

(iii) $25 \%$ of $\frac{1}{8}$

 Sol: $\frac{25}{100} \times \frac{1}{8}$

$=\frac{1}{4} \times \frac{1}{8}$

$=\frac{1}{32}$

(iv) 4.5% of 60cm 

Sol: $=\frac{4.5}{100 \times 10} \times 60$

$=\frac{27}{10}=2.7 \mathrm{~cm}$

(v) $7 \frac{1}{2} \%$ of $₹ 56$

Sol: $\frac{15}{2 \times 100}\times 56$

$=\frac{42}{10}=Rs 4.2$

(vi) 60% of 1 year 

Sol: $\frac{60}{100} \times 365$

=219 days 

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Q7 | Ex-9A | Class 7 | SChand Composite Maths | Percentage and it's application | myhelper

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Question 7

What percent is : 

(i) 25 of 60 

Sol: $\frac{25}{60} \times 100=\frac{250}{6}=41 \frac{4}{6}$

(ii) 7.5 of 150 

Sol: $\frac{7.5}{150} \times 100$

= 5% answer 

(iii) 5 paise of Rs 5 

Sol: $\frac{5}{500} \times 100=1 \%$

(iv) $2 \frac{1}{2} \mathrm{~cm}$ of $10 \mathrm{~cm}$

Sol:  $\frac{2.5}{10} \times 100=25 \%$

(v) 55m to 1 km 

Sol: 1km = 1000m

=$\frac{55}{1000} \times 100$

=5.5 %

(vi) 40 sec of 2min 40 sec 

Sol: $\frac{40}{160} \times 100$

= 25% 

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Q8 | Ex-9A | Class 7 | SChand Composite Maths | Percentage and it's application | myhelper

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Question 8

Find the number whose: 

(i) 14 % is 28 

Sol: Let the number is x

=14 % of x = 28 = $\frac{14}{100} \times x=28$

=  $x=28 \times \frac{100}{14}=200$ Answer 

 

(ii) $16 \frac{2}{3} \%$ is 3

Sol: $\frac{50}{300} \times x=3 \Rightarrow x=3 \times \frac{30}{5}$

x=18 answer 

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Question 9

What is the length whose 30 % is 24 cm ?

Sol: Let the length be x 

= $30 \%  of  x=24 \Rightarrow \frac{30}{100} \times x=24$

=x =$24 \times \frac{100}{30}$

x= 80 answer 

(ii) What is the volume of whose $16 \frac{2}{3} \%$ is 0.75 L ? 

Sol: 

$\frac{50}{3} \div 100  \times x=\frac{75}{100}$

$\frac{50}{3} \times \frac{1}{100}  \times x=\frac{75}{100}$

$\frac{x}{6}=\frac{75}{100}$

$x=\frac{75}{100} \times 6$

$x=\frac{450}{100}=4.5$ L

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Question 10

What is the % change when 

(i) 25 is increased to 45 

Change = 45-25= 20

%Increase =  $\frac{Amount increase}{Original amount}\times 100$

$\frac{20}{25} \times 100=80 \%$

(ii) 200 is decreased to 190 

Decrease = 200- 190 = 10 

% Decrease = $\frac{10}{200} \times 100$

=5%

(iii) 64 is increased to 144 

Increase = 14 -64 = 80 

% Increase =  $\frac{80}{64} \times 100=\frac{1000}{8}=125 \%$

(iv) 320 is decreased to 288

Decrease = 320 - 288= 32

% Decrease = $\frac{32}{320} \times 100$

=10%

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Q11 | Ex-9A | Class 7 | SChand Composite Maths | Percentage and it's application | myhelper

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Question 11

Increase 

(i) Rs 80 by 5% 

Sol: 5% Of 80 = Amount of increase 

= $\frac{5}{100} \times 80=Rs 4$

∴ Increased amount = Original + Increase 

$=80+4=Rs 84$

(ii) 440 By 80 %

Sol: Increase = 80 % of 440 = $\frac{80}{100} \times 44 0$

= 352

∴   Increase amount  = 440+ 352 = Rs 792 answer 

(iii) Rs 120 By $33 \frac{1}{3} \%$

 Sol: Increase = $\frac{100}{3} \% of 120$

= $\frac{100}{300} \times 120$

= Rs 40 

∴   Increase amount  =  120 + 40 = Rs 160 Answer 

(iv) 44 by 2.5 % 

Sol: Increase  = 2.5 % of 44 = 1.1

∴   Increase amount   = 44+ 1.1= 45.1 Answer

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Q12 | Ex-9A | Class 7 | SChand Composite Maths | Percentage and it's application | myhelper

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Question 12

Decrease : 

(i) 400 by 25% 

Decrease % = 25% of 400 = $\frac{25}{100} \times 400=100$

Total 

Decrease = Original - Decrease 

400- 100= 300 answer 

(ii) Rs 8 by 12 % 

Decrease % = 12% of 8 

$=\frac{96}{100}=0.96$

Decrease amount = 8- 0.96 = Rs 7.04 answer

(iii) 150 by $33 \frac{1}{3} \%$

Sol: Decrease %= $\frac{100}{3} \% of 150=$ $\frac{100}{3 \times 100} \times 150$ =50

Decrease = 150 -50 = 100 answer 

(iv) 500 by $12.5 \%$

Sol: Decrease % = 12.5% of 500

$\frac{12.5}{100} \times 500=62.5$

Decrease amount = $500-62.5$

= 437.5 answer