Exercise 2.7
Q 1, Ex 2.7 - Fractions and Decimals - Chapter 2 - Maths Class 7th - NCERT
Find:
(i) $0.4 \div 2$
Sol :
$0.4 \div 2$ $=\dfrac{4}{10} \div 2$
(ii) $0.35 \div 5$
Sol :
$0.35 \div 5$ $=\dfrac{35}{100} \div 5$ $=\dfrac{35}{100} \times \dfrac{1}{5}$ $=\dfrac{7}{100}$ = 0.07
(iii) $2.48 \div 4$
Sol :
$2.48 \div 4$ $=\dfrac{248}{100} \div 4$ $=\dfrac{248}{100} \times \dfrac{1}{4}$ $=\dfrac{62}{100}$ = 0.62
(iv) $65.4 \div 6$
Sol :
$65.4 \div 6$ $=\dfrac{654}{10} \div 6$ $\dfrac{654}{10} \times \dfrac{1}{6}$ $=\dfrac{109}{10}$ = 10.9
(v) $651.2 \div 4$
Sol :
$651.2 \div 4$ $=\dfrac{6512}{10} \div 4$ $=\dfrac{6512}{10} \times \dfrac{1}{4}$ $=\dfrac{1628}{10}$ = 162.8
(vi) $14.49 \div 7$
Sol :
$14.49 \div 7$ $=\dfrac{1449}{100} \div 7 $ $=\dfrac{1449}{100} \times \dfrac{1}{7}$ $=\dfrac{207}{100}$ = 2.07
(vii) $3.96 \div 4$
Sol :
$3.96 \div 4$ $=\dfrac{396}{100} \div 4$ $=\dfrac{396}{100} \times \dfrac{1}{4}$ $=\dfrac{99}{100}$ = 0.99
(viii) $0.80 \div 5$
Sol :
$0.80 \div 5$ $=\dfrac{80}{100} \div 5$ $=\dfrac{80}{100} \times \dfrac{1}{5}$ $=\dfrac{16}{100}$ =0.16
Q 2, Ex 2.7 - Fractions and Decimals - Chapter 2 - Maths Class 7th - NCERT
Question 2
Find:
(i) $4.8 \div 10$
Sol : 0.48
(ii) $52.5 \div 10$
Sol : 5.25
(iii) $0.7 \div 10$
Sol : 0.07
(iv) $33.1 \div 10$
Sol : 3.31
(v) $272.23 \div 10$
Sol : 27.223
(vi) $0.56 \div 10$
Sol : 0.056
(vii) $397\div 10$
Sol : 0.397
Note : We know that when a decimal number is divided by a multiple of 10 only (i.e., 10, 100, 1000, etc.), the decimal point will be shifted to the left by as many places as there are zeroes. Since here we are dividing by 10, the decimal will shift to the left by 1 place.
Q 3, Ex 2.7 - Fractions and Decimals - Chapter 2 - Maths Class 7th - NCERT
Question 3
Find:
(i) $2.7 \div 100$
Sol : 0.027
(ii) $0.3 \div 100$
Sol : 0.003
(iii) $0.78 \div 100$
Sol : 0.0078
(iv) $432.6 \div 100$
Sol : 4.326
(v) $23.6 \div 100$
Sol : 0.236
(vi) $98.53 \div 100$
Sol : 0.9853
Notes : We know that when a decimal number is divided by a multiple of 10 only (i.e., 10, 100, 1000, etc.), the decimal point will be shifted to the left by as many places as there are zeroes. Since here we are dividing by 100, the decimal will shift to the left by 2 places.
Q 4, Ex 2.7 - Fractions and Decimals - Chapter 2 - Maths Class 7th - NCERT
Find:
(i) $7.9 \div 1000$
Sol : 0.0079
(ii) $26.3 \div 1000$
Sol : 0.0263
(iii) $38.53 \div 1000$
Sol : 0.03853
(iv) $128.9 \div 1000$
Sol : 0.1289
(v) $0.5 \div 1000$
Sol : 0.0005
Q 5, Ex 2.7 - Fractions and Decimals - Chapter 2 - Maths Class 7th - NCERT
Question 5
Find:
(i) $7 \div 3.5$
Sol :
$7 \div 3.5$ $=7 \div \dfrac{35}{10}$ $=35 \times \dfrac{10}{35}$ = 2
(ii) $36 \div 0.2$
Sol :
$36 \div 0.2$ $=36 \div \dfrac{2}{10}$ $=36 \times \dfrac{10}{2}$ = 180
(iii) $3.25 \div 0.5$
Sol :
$3.25 \div 0.5$ $=\dfrac{325}{100} \div \dfrac{5}{10}$ $=\dfrac{325}{100} \times \dfrac{10}{5}$ $=\dfrac{65}{10}$ = 6.5
(iv) $30.94\div 0.7$
Sol :
$30.94\div 0.7$ $=\dfrac{3094}{100} \div \dfrac{7}{10}$ $=\dfrac{3094}{100} \times \dfrac{7}{10}$ $=\dfrac{442}{10}$ = 44.2
(v) $0.5 \div 0.25$
Sol :
$0.5 \div 0.25$ $=\dfrac{5}{10} \div \dfrac{25}{100}$ $=\dfrac{5}{10} \times \dfrac{100}{25}$ = 2
(vi) $7.75 \div 0.25$
Sol :
$7.75 \div 0.25$ $=\dfrac{775}{100} \div \dfrac{25}{100}$ $=\dfrac{775}{100} \times \dfrac{100}{25}$ = 31
(vii) $76.5 \div 0.15$
Sol :
$76.5 \div 0.15$ $=\dfrac{765}{10} \div \dfrac{15}{100}$ $=\dfrac{765}{10} \times \dfrac{100}{15}$ = 510
(viii) $37.8 \div 1.4$
Sol :
$37.8 \div 1.4$ $=\dfrac{378}{10} \div \dfrac{14}{10}$ $=\dfrac{378}{10} \times \dfrac{10}{14}$ = 27
(ix) $2.73 \div 1.3$
Sol :
$2.73 \div 1.3$ $=\dfrac{273}{100} \div \dfrac{13}{10}$ $=\dfrac{273}{100} \times \dfrac{10}{13}$ $=\dfrac{21}{10}$ = 2.1
Q 6, Ex 2.7 - Fractions and Decimals - Chapter 2 - Maths Class 7th - NCERT
Question 6
A vehicle covers a distance of 43.2 km in 2.4 litres of petrol. How much distance will it cover in one litre of petrol?
Sol :
Distance covered in 2.4 litres of petrol = 43.2 km
$\therefore$ Distance covered in 1 litre of petrol $=43.2\div 2.4$ $=\dfrac{432}{10} \div \dfrac{24}{10}$ $=\dfrac{432}{10} \div \dfrac{10}{24}$ = 18
Therefore, the vehicle will cover 18 km in 1 litre petrol.
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