EXERCISE:7.1
Question 1
i) $25 \%=\frac{25}{100}=\frac{1}{4}$
ii) $150 \%=\frac{150}{100}=\frac{3}{2}$.
iii) $7 \frac{1}{2} \%=\frac{15}{2} \%=\frac{15 / 2}{100}=\frac{15}{2 \times 100}=\frac{3}{40}$
iv) $33 \frac{1}{3} \%=\frac{100}{3} \%=\frac{100 / 3}{100}=\frac{100}{3 \times 100}=\frac{1}{3} .$
Question 2
i) $\frac{1}{8}=\left(\frac{1}{8} \times 100\right) \%=12.5 \%$
ii) $\frac{5}{4}=\left(\frac{5}{4} \times 100\right) \%=125 \%$
iii) $\frac{9}{16}=\left(\frac{9}{16} \times 100\right) \%=56 \frac{1}{4} \%$
iv) $\frac{3}{7}=\left(\frac{3}{2} \times 100\right) \%=42 \frac{6}{7} \%$
v) $\frac{11}{15}=\left(\frac{11}{15} \times 100\right) \%=73 \frac{1}{3} \%$
vi) $\frac{13}{8}=\frac{11}{8}=\left(\frac{11}{8} \times 100\right) \%=137 \frac{1}{2} \%$
Question 3
i) Given 6 students out of 40 students in a class are absent
percentage of students are absent $=\frac{6}{40} \times 100 \%$
=15%
ii) Given, Antony secured 384 marks out of 500 maiks.
$\therefore$ percentage of marks secured $=\left(\frac{384}{500} \times 100\right) \%$
$=76.8 \%$
iii) Given , A shop has 500 shirts
Out of 500 shirts , 15 are defective
Now, percentage of shirts are defective = $\left(\frac{15}{500} \times 100\right) \%$
=3%
iv) Given,
Vani has 20 gold bangels
Also she has 10 silver bangles
Now, Total number of bangles = 20+ 10 = 30 bangles
∴ percentage of gold bangles = ($\left.\frac{20}{30} \times 100\right) \%$
=66.67 %
$\begin{aligned} \text { percentage of Silver bangles } &=\left(\frac{10}{30} \times 100\right) \% \\ &=33.34 \% \end{aligned}$
v) Total number of voters = 120
Out of 120 , 90 of them voted
Then out of 120, votes did not vote = 120-90=30
ஃPercentage of voters did not vote = $\frac{30}{120} \times 100 \%$
=$25 \%$
Question 4
i) Shaded part $=\frac{3}{4}$
percentage of Shaded part $=\left(\frac{3}{4} \times 100\right) \%$
$=75 \%$
ii) Shaded part $=\frac{2}{6}=\frac{1}{3}$
percentage of Shaded part $=\left(\frac{1}{3} \times 100\right) \%$
$=33.34 \%$
iii) Shaded part $=\frac{5}{8}$
percentage of shaded part $=\left(\frac{5}{8} \times 100\right) \%=62.5 \%$
Question 5
i) $14 \%=\frac{14}{100}=\frac{7}{50} .$
ii) $1 \frac{3}{4} \%=\frac{7}{4} \%=\frac{7}{4 \times 100}=\frac{7}{400} .$
iii) $33 \frac{1}{3} \%=\frac{100}{3} \%=\frac{100}{3 \times 100}=\frac{1}{3} .$
iv) $37.5 \%=\frac{37.5}{100}=\frac{375}{1000}=\frac{3}{8} .$
Question 6
i) $\frac{5}{4}=\left(\frac{5}{4} \times 100\right) \%=125 \%$
ii) $\frac{1}{1}=\left(\frac{1}{1} \times 100\right) \%=100 \%$
iii) $\frac{2}{3}=\left(\frac{2}{3} \times 100\right) \%=66.67 \%$
iv) $\frac{9}{16}=\left(\frac{9}{16} \times 100\right) \%=56.25 \%$
Question 7
Given alloy consists of 7 parts of zinc and 33 parts of copper
Total alloy contains = 33+ 7 = 40
ஃ percentage of copper in alloy = $\left(\frac{33}{40} \times 100\right) \%$
=$82.5 \%$
Question 8
Given , Calcium, carbon and sand in the ratio 12:3:10
Sum of ratio = 12+ 3+ 10 = 25
Percentage of carbon in the chalk = ($\frac{3}{25} \times 100$) % =12%
Question 9
Given Total money = Rs 2500
It is divided among Ravi, Raju and Roy
Out of total money , ravi gets two parts
Raju gets three parts
Roy gets five parts
Total no. of parts = 2+ 3+ 5= 10
Ravi get money = Rs $\frac{2}{10} \times 2500$
=Rs 500
$\begin{aligned} \text { Raju gets money } &=3 \frac{3}{10} \times 2500 \\ &= 750 rs. \\ \text { Roy gets money } &= \frac{5}{10} \times 2500 \\ &= 1250 rs . \end{aligned}$
Percentage of Ravi get money $\begin{aligned} &=\left(\frac{500}{2500} \times 100\right) \% \\ &=20 \% \end{aligned}$
$\begin{aligned} \text { percentage of Raju gets money } &=\left(\frac{750}{2500} \times 100\right) \% \\ &=30 \% \end{aligned}$
$\begin{aligned} \text { Percentage of Roy geT money } &=\left(\frac{1250}{2500} \times 100\right) \% \\ &=50 \% \end{aligned}$
Question 10
i) $28 \%=\frac{28}{100}=0.28 .$
ii) $3 \%=\frac{3}{100}=0.03$
iii) $0.44 \%=\frac{0.44}{100}=0.0044$
iv) $37 \frac{1}{2} \%=\frac{75}{2} \%=\frac{75}{2 \times 100}=0.335$
Question 11
i) $0.65=\frac{65}{100}=\left(\frac{65}{100} \times 100\right) \%=65 \%$
ii) $0.90=\frac{90}{100}=\left(\frac{90}{100} \times 100\right) \%=90 \%$
iii) $2.1=\frac{21}{10}=\left(\frac{21}{10} \times 100\right) \%=210 \%$
iv) $0.02=\frac{2}{100}=\left(\frac{2}{100} \times 100\right) \%=2 \%$
Question 12
i) Given percentage of students in a class are girls = 42%
Actual percentage of students in a class will be 100%
Percentage of students in a class are boys = (100-42)% =58%
ii) A basket have full of apples , oranges and mangoes
Percentage of apples = 50 %
Percentage of oranges = 30%
Percentage of total oranges , apples and mangoes = 100 %
ஃNow percentage of mangoes = [100-(50+30)]%
=[100-80] %
=20 %
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