Exercise 2.5 (Revised) - Chapter 2 - Fractions & Decimals - Ncert Solutions class 7 - Maths

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Chapter 2: Fractions & Decimals - NCERT Solutions for Class 7 Maths

Ex 2.5 Question 1.

Find:
(i) $0.4 \div 2$
(ii) $0.35 \div 5$
(iii) $2.48 \div 4$
(iv) $65.4 \div 6$
(v) $651.2 \div 4$
(v) $14.49 \div 7$
(vii) $3.96 \div 4$
(viii) $0.80 \div 5$

Answer:

(i) $0.4 \div 2=\frac{4}{10} \times \frac{1}{2}=\frac{2}{10}=0.2$
(ii) $0.35 \div 5=\frac{35}{100} \times \frac{1}{5}=\frac{7}{100}=0.07$
(iii) $2.48 \div 4=\frac{248}{100} \times \frac{1}{4}=\frac{62}{100}=0.62$
(iv) $65.4 \div 6=\frac{654}{10} \times \frac{1}{6}=\frac{109}{10}=10.9$
(v) $651.2 \div 4=\frac{6512}{10} \times \frac{1}{4}=\frac{1628}{10}=162.8$
(vi) $14.49 \div 7=\frac{1449}{100} \times \frac{1}{7}=\frac{207}{100}=2.07$
(vii) $3.96 \div 4=\frac{396}{100} \times \frac{1}{4}=\frac{99}{100}=0.99$
(viii) $0.80 \div 5=\frac{80}{100} \times \frac{1}{5}=\frac{16}{100}=0.16$

Ex 2.5 Question 2.

Find:
(i) $4.8 \div 10$
(ii) $52.5 \div 10$
(iii) $0.7 \div 10$

(iv) $33.1 \div 10$
(v) $272.23 \div 10$
(vi) $0.56 \div 10$
(vii) $3.97 \div 10$

Answer:

(i) $4.8 \div 10=\frac{4.8}{10}=0.48$
(ii) $52.5 \div 10=\frac{52.5}{10}=5.25$
(iii) $0.7 \div 10=\frac{0.7}{10}=0.07$
(iv) $33.1 \div 10=\frac{33.1}{10}=3.31$
(v) $272.23 \div 10=\frac{272.23}{10}=27.223$
(vi) $0.56 \div 10=\frac{0.56}{10}=0.056$
(vii) $3.97 \div 10=\frac{3.97}{10}=0.397$

Ex 2.5 Question 3.

Find:
(i) $2.7 \div 100$
(ii) $0.3 \div 100$
(iii) $0.78 \div 100$
(iv) $432.6 \div 100$

(v) $23.6 \div 100$
(vi) $98.53 \div 100$

Answer:

(i) $2.7 \div 100=\frac{27}{10} \times \frac{1}{100}=\frac{27}{1000}=0.027$
(ii) $0.3 \div 100=\frac{3}{10} \times \frac{1}{100}=\frac{3}{1000}=0.003$
(iii) $0.78 \div 100=\frac{78}{100} \times \frac{1}{100}=\frac{78}{10000}=0.0078$

(iv) $432.6 \div 100=\frac{4326}{10} \times \frac{1}{100}=\frac{4326}{1000}=4.326$
(v) $23.6 \div 100=\frac{236}{10} \times \frac{1}{100}=\frac{236}{1000}=0.236$
(vi) $98.53 \div 100=\frac{9853}{100} \times \frac{1}{100}=\frac{9853}{10000} 0.9853$

Ex 2.5 Question 4.

Find:
(i) $7.9 \div 1000$
(ii) $26.3 \div 1000$
(iii) $38.53 \div 1000$
(iv) $128.9 \div 1000$
(v) $0.5 \div 1000$

Answer:

(i) $7.9 \div 1000=\frac{79}{10} \times \frac{1}{1000}=\frac{79}{10000}=0.0079$
(ii) $26.3 \div 1000=\frac{263}{10} \times \frac{1}{1000}=\frac{263}{10000}=0.0263$
(iii) $38.53 \div 1000=\frac{3853}{100} \times \frac{1}{1000}=\frac{3853}{100000}=0.03853$
(iv) $128.9 \div 1000=\frac{1289}{10} \times \frac{1}{1000}=\frac{1289}{10000}=0.1289$
(v) $0.5 \div 1000=\frac{5}{10} \times \frac{1}{1000}=\frac{5}{10000}=0.0005$

Ex 2.5 Question 5.

Find:
(i) $7 \div 3.5$
(ii) $36 \div 0.2$
(iii) $3.25 \div 0.5$
(iv) $30.94 \div 0.7$
(v) $0.5 \div 0.25$
(vi) $7.75 \div 0.25$

(vii) $76.5 \div 0.15$
(viii) $37.8 \div 1.4$
(ix) $2.73 \div 1.3$

Answer:

(i) $7 \div 3.5=7 \div \frac{35}{10}=7 \times \frac{10}{35}=\frac{10}{5}=2$
(ii) $36 \div 0.2=36 \div \frac{2}{10}=36 \times \frac{10}{2}=18 \times 10=180$
(iii) $3.25 \div 0.5=\frac{325}{100} \div \frac{5}{10}=\frac{325}{100} \times \frac{10}{5}=\frac{65}{10}=6.5$
(iv) $30.94 \div 0.7=\frac{3094}{100} \div \frac{7}{10}=\frac{3094}{100} \times \frac{10}{7}=\frac{442}{10}=44.2$
(v) $0.5 \div 0.25=\frac{5}{10} \div \frac{25}{100}=\frac{5}{10} \times \frac{100}{25}=\frac{10}{5}=2$
(vi) $7.75 \div 0.25=\frac{775}{100} \div \frac{25}{100}=\frac{775}{100} \times \frac{100}{25}=31$
(vii) $76.5 \div 0.15=\frac{765}{10} \div \frac{15}{100}=\frac{765}{10} \times \frac{100}{15}=51 \times 10=510$
(viii) $37.8 \div 1.4=\frac{378}{10} \div \frac{14}{10}=\frac{378}{10} \times \frac{10}{14}=27$
(ix) $2.73 \div 1.3=\frac{273}{100} \div \frac{13}{10}=\frac{273}{100} \times \frac{10}{13}=\frac{21}{10}=2.1$

Ex 2.5 Question 6.

A vehicle covers a distance of $43.2 \mathrm{~km}$ in 2.4 litres of petrol. How much distance will it cover in one litre petrol?

Answer:

$\because$ In 2.4 litres of petrol, distance covered by the vehicle $=43.2 \mathrm{~km}$
$\therefore$ In 1 litre of petrol, distance covered by the vehicle $=43.2 \div 2.4$
$
\begin{aligned}
& =\frac{432}{10} \div \frac{24}{10}=\frac{432}{10} \times \frac{10}{24} \\
& =18 \mathrm{~km}
\end{aligned}
$

Thus, it covered $18 \mathrm{~km}$ distance in one litre of petrol.