S.chand publication New Learning Composite mathematics solution of class 7 Chapter 8 Percentage and Its Applications Exercise 8A

 Exercise 8A

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Q1 | Ex-8A |Class 7 |S.Chand | New Learning Composite maths |Percentage and Its Applications |Ch-7 |myhelper

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Question 1

Express each of the following as a percentage.

(a) 

(i) $\frac{1}{5}$

Sol : $\frac{1}{5} \times 100$=20%

(ii) $\frac{3}{4}$

Sol : $\frac{3}{4} \times 100$=75%

(iii) $\frac{17}{50}$ 

Sol : $\frac{17}{50} \times 100$=34%

(iv) $\frac{11}{20}$ 

Sol : $\frac{11}{20} \times 100$=55%

(v) $2\frac{9}{10}$

Sol : $\frac{29}{10}\times 100$=290%

(vi) $2\frac{8}{25}$

Sol : $\frac{58}{25}\times 100$=232%

(b) 

(i) 0.3 

Sol : 0.3×100=30%

(ii) 0.47 

Sol : 0.89×100=89%

(iii) 0.89 

Sol : 0.89×100=89%

(iv) 1.05 

Sol : 1.05×100=105%

(v) 0.09 

Sol : 0.09×100=9%

(vi) 0.769 

Sol : 0.769×100=76.9%

(vii) 3 

Sol : 3×100=300%

(viii) 9.002 

Sol : 9.002×100=900.2%

(ix) 2.25 

Sol : 2.25×100%

(x) 0.75

Sol : 0.75×100=75%

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Q2 | Ex-8A |Class 7 |S.Chand | New Learning Composite maths |Percentage and Its Applications |Ch-7 |myhelper

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Question 2

Express as a fraction in its simplest form.

(a) 80% 

Sol : $=\frac{80}{100}=\frac{4}{5}$

(b) 36% 

Sol : $\frac{36}{100}=\frac{9}{25}$

(c) 60% 

Sol : $\frac{60}{100}=\frac{3}{5}$

(d) 19% 

Sol : $\frac{19}{100}$

(e) $62\frac{1}{2}$% 

Sol : $\dfrac{\frac{125}{2}}{100}=\frac{125}{100}=\frac{5}{8}$

(f) $133\frac{1}{3}$% 

Sol : $\dfrac{\frac{400}{3}}{100}=\frac{400}{300}=1\frac{1}{3}$

(g) 120% 

Sol : $\frac{120}{100}=1\frac{1}{5}$

(h) 65% 

Sol : $\frac{65}{100}=\frac{13}{20}$

(i) 270% 

Sol : $\frac{270}{100}=2\frac{7}{10}$

(j) 350%

Sol : $\frac{350}{100}=\frac{7}{2}=3\frac{1}{2}$

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Q3 | Ex-8A |Class 7 |S.Chand | New Learning Composite maths |Percentage and Its Applications |Ch-7 |myhelper

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Question 3

Express as a decimal.

(a) 7% 

Sol : $\frac{7}{100}$=0.07

(b) 80% 

Sol : $\frac{80}{100}$=0.8

(c) 72% 

Sol : $\frac{72}{100}$ =0.72

(d) 39% 

Sol : $\frac{39}{100}$=0.39

(e) $1\frac{1}{2}$% 

Sol : $\frac{3}{2}=\frac{15}{100}$

=0.01

(f) $6\frac{1}{4}$% 

Sol : $\frac{24}{4}=\frac{6.25}{100}$

=0.0625

(g) $27\frac{1}{2}$% 

Sol : $\frac{55}{2}=\frac{27.5}{100}$

=0.275

(h) $72\frac{3}{5}$% 

Sol : $\frac{363}{5}=\frac{72.6}{100}$

=0.726

(i) 189% 

Sol : $\frac{189}{100}$

=1.89

(j) $205\frac{2}{5}$%

Sol : $\frac{1027}{5}=\frac{205.4}{100}$

=2.054

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Q4 | Ex-8A |Class 7 |S.Chand | New Learning Composite maths |Percentage and Its Applications |Ch-7 |myhelper

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Question 4

Compare and Write <,> or = in the box.

(a) $\frac{5}{8}$ ___ 70%

Sol :

$\frac{5}{8}\times 100$=62.5%

$\frac{5}{8} < 70\%$

(b) 64% ___ $\frac{3}{5}$

Sol :

$\frac{3}{5}\times 100$=60%

64% >$\frac{3}{5}$

(c) 92.7% ___ 0.927

Sol :

0.927=0.927×100%=92.7%

∴92.7% = 0.927

(d) 0.99 ____ 100%

Sol :

0.99=0.99×100%=99%

∴0.99<100%

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Q5 | Ex-8A |Class 7 |S.Chand | New Learning Composite maths |Percentage and Its Applications |Ch-7 |myhelper

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Question 5

Arrange in ascending order.

(a) 38%, 0.4, $35\frac{1}{3}$%, $\frac{5}{8}$

Sol :

0.4=0.4×100%=40%

$35\frac{1}{3}=\frac{106}{3}$=35.33%

$\frac{5}{8}=\frac{5}{8}\times 100$%=62.5%

Ans : $35\frac{1}{3}$% , 38%, 0.4, $\frac{5}{8}$

(b) 0.93, 19.20, $1\frac{2}{3}$, 67%

Sol :

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Question 6

Arrange in descending order.

(a) $\frac{4}{5}$, 0.5, 500%,$66\frac{2}{3}$%

Sol : 

(b) $\frac{7}{20}$, 0.038, 39%, 0.59

Sol :

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Question 7

Use the following diagrams to complete the table

(a)

(b)

(c)

(d) 

	Fraction shaded	Percentage shaded	Percentage unshaded
(a)	$\frac{3}{4}$	75%	25%
(b)	$\frac{9}{15}=\frac{3}{5}$	60%	40%
(c)	$\frac{2}{5}$	40%	60%
(d)	$\frac{5}{8}$	$62\frac{1}{2}$%	$37\frac{1}{2}$%

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Q8 | Ex-8A |Class 7 |S.Chand | New Learning Composite maths |Percentage and Its Applications |Ch-7 |myhelper

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Question 8

A molecular of water is made up of 2 atoms of hydrogen and 1 atom of oxygen. What percent of the atoms a water molecular is oxygen?

Sol :

∴Percentage of oxygen in water $=\frac{1}{3}\times 100$%$=33\frac{1}{3}$%

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Q9 | Ex-8A |Class 7 |S.Chand | New Learning Composite maths |Percentage and Its Applications |Ch-7 |myhelper

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Question 9

Sterling silver is an alloy combining 925 parts of pure silver and 75 parts of another metal, such as copper. What percent of sterling silver is not pure silver?

Sol :

∴Percentage of sterling silver$=\frac{75}{(925+75)}\times 100$%

$=\frac{75}{1000}\times 100$

=7.5%

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Question 10

Prashant spends 4 hours a day on his self study, 1 hour playing video games and 1 hour in doing workouts at fitness centre. What per cent of the day does Prahant spend on these activities?

Sol :

∴Prashant spend time on these activities 

$=\frac{(4+1+1)}{24}\times 100$%

$=\frac{6}{24}\times 100$%

=25%