NCERT Answers for Class 7 Maths
Chapter 2 Fractions and Decimals Exercise 2.7
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Chapter 2 Exercise 2.1 |
Page 52
Ex 2.7 Class 7 Maths Question 1. Find:
(i) 0.4 ÷ 2 (ii) 0.35 ÷ 5 (iii) 2.48 ÷ 4 (iv) 65.4 ÷ 6
(v) 651.2 ÷ 4 (vi) 14.49 ÷ 7 (vii) 3.96 ÷ 4 (viii) 0.80 ÷ 5
(i) 0.4 ÷ 2
Answer
= (4/10) ÷ 2
= (4/10) × (1/2)
= (2/10) × (1/1)
= (2/10)
On dividing a decimal by 10, the decimal point is shifted to the left by one place.
= 0.2
(ii) 0.35 ÷ 5
Answer
= (35/100) ÷ 5
= (35/100) × (1/5)
= (7/100) × (1/1)
= (7/100)
On dividing a decimal by 100, the decimal point is shifted to the left by two places.
= 0.07
(iii) 2.48 ÷ 4
Answer
= (248/100) ÷ 4
= (248/100) × (1/4)
= (62/100) × (1/1)
= (62/100)
On dividing a decimal by 100, the decimal point is shifted to the left by two places.
= 0.62
(iv) 65.4 ÷ 6
Answer
= (654/10) ÷ 6
= (654/10) × (1/6)
= (109/10) × (1/1)
= (109/10)
On dividing a decimal by 10, the decimal point is shifted to the left by one place.
= 10.9
(v) 651.2 ÷ 4
Answer
= (6512/10) ÷ 4
= (6512/10) × (1/4)
= (1628/10) × (1/1)
= (1628/10)
On dividing a decimal by 10, the decimal point is shifted to the left by one place.
= 162.8
(vi) 14.49 ÷ 7
Answer
= (1449/100) ÷ 7
= (1449/100) × (1/7)
= (207/100) × (1/1)
= (207/100)
On dividing a decimal by 100, the decimal point is shifted to the left by two places.
= 2.07
(vii) 3.96 ÷ 4
Answer
= (396/100) ÷ 4
= (396/100) × (1/4)
= (99/100) × (1/1)
= (99/100)
On dividing a decimal by 100, the decimal point is shifted to the left by two places.
= 0.99
(viii) 0.80 ÷ 5
Answer
= (80/100) ÷ 5
= (80/100) × (1/5)
= (16/100) × (1/1)
= (16/100)
On dividing a decimal by 100, the decimal point is shifted to the left by two places.
= 0.16
2. Find:
(i) 4.8 ÷ 10 (ii) 52.5 ÷ 10 (iii) 0.7 ÷ 10 (iv) 33.1 ÷ 10
(v) 272.23 ÷ 10 (vi) 0.56 ÷ 10 (vii) 3.97 ÷10
Answer
On dividing a decimal by 10, the decimal point is shifted to the left by one place.
= 4.8 ÷ 10
= (4.8/10)
= 0.48
(ii) 52.5 ÷ 10
Answer
On dividing a decimal by 10, the decimal point is shifted to the left by one place.
= 52.5 ÷ 10
= (52.5/10)
= 5.25
(iii) 0.7 ÷ 10
Answer
On dividing a decimal by 10, the decimal point is shifted to the left by one place.
= 0.7 ÷ 10
= (0.7/10)
= 0.07
(iv) 33.1 ÷ 10
Answer
On dividing a decimal by 10, the decimal point is shifted to the left by one place.
= 33.1 ÷ 10
= (33.1/10)
= 3.31
(v) 272.23 ÷ 10
Answer
On dividing a decimal by 10, the decimal point is shifted to the left by one place.
= 272.23 ÷ 10
= (272.23/10)
= 27.223
(vi) 0.56 ÷ 10
Answer
On dividing a decimal by 10, the decimal point is shifted to the left by one place.
= 0.56 ÷ 10
= (0.56/10)
= 0.056
(vii) 3.97 ÷10
Answer
On dividing a decimal by 10, the decimal point is shifted to the left by one place.
= 3.97 ÷ 10
= (3.97/10)
= 0.397
3. Find:
(i) 2.7 ÷ 100 (ii) 0.3 ÷ 100 (iii) 0.78 ÷ 100
(iv) 432.6 ÷ 100 (v) 23.6 ÷100 (vi) 98.53 ÷ 100
(i) 2.7 ÷ 100
Answer
On dividing a decimal by 100, the decimal point is shifted to the left by two places.
= 2.7 ÷ 100
= (2.7/100)
= 0.027
(ii) 0.3 ÷ 100
Answer
On dividing a decimal by 100, the decimal point is shifted to the left by two places.
= 0.3 ÷ 100
= (0.3/100)
= 0.003
(iii) 0.78 ÷ 100
Answer
On dividing a decimal by 100, the decimal point is shifted to the left by two places.
= 0.78 ÷ 100
= (0.78/100)
= 0.0078
(iv) 432.6 ÷ 100
Answer
On dividing a decimal by 100, the decimal point is shifted to the left by two places.
= 432.6 ÷ 100
= (432.6/100)
= 4.326
(v) 23.6 ÷100
Answer
On dividing a decimal by 100, the decimal point is shifted to the left by two places.
= 23.6 ÷ 100
= (23.6/100)
= 0.236
(vi) 98.53 ÷ 100
Answer
On dividing a decimal by 100, the decimal point is shifted to the left by two places.
= 98.53 ÷ 100
= (98.53/100)
= 0.9853
4. Find:
(i) 7.9 ÷ 1000 (ii) 26.3 ÷ 1000 (iii) 38.53 ÷ 1000
(iv) 128.9 ÷ 1000 (v) 0.5 ÷ 1000
(i) 7.9 ÷ 1000
Answer
On dividing a decimal by 1000, the decimal point is shifted to the left by three places.
= 7.9 ÷ 1000
= (7.9/1000)
= 0.0079
(ii) 26.3 ÷ 1000
Answer
On dividing a decimal by 1000, the decimal point is shifted to the left by three places.
= 26.3 ÷ 1000
= (26.3/1000)
= 0.0263
(iii) 38.53 ÷ 1000
Answer
On dividing a decimal by 1000, the decimal point is shifted to the left by three places.
= 38.53 ÷ 1000
= (38.53/1000)
= 0.03853
(iv) 128.9 ÷ 1000
Answer
On dividing a decimal by 1000, the decimal point is shifted to the left by three places.
= 128.9 ÷ 1000
= (128.9/1000)
= 0.1289
(v) 0.5 ÷ 1000
Answer
On dividing a decimal by 1000, the decimal point is shifted to the left by three places.
= 0.5 ÷ 1000
= (0.5/1000)
= 0.0005
5. Find:
(i) 7 ÷ 3.5 (ii) 36 ÷ 0.2 (iii) 3.25 ÷ 0.5 (iv) 30.94 ÷ 0.7
(v) 0.5 ÷ 0.25 (vi) 7.75 ÷ 0.25 (vii) 76.5 ÷ 0.15 (viii) 37.8 ÷ 1.4
(ix) 2.73 ÷ 1.3
(i) 7 ÷ 3.5
Answer
= 7 ÷ (35/10)
= 7 × (10/35)
= 1 × (10/5)
= 2
(ii) 36 ÷ 0.2
Answer
= 36 ÷ (2/10)
= 36 × (10/2)
= 18 × 10
= 180
(iii) 3.25 ÷ 0.5
Answer
= (325/100) ÷ (5/10)
= (325/100) × (10/5)
= (325 × 10)/ (100 × 5)
= (65 × 1)/ (10 × 1)
= 65/10
= 6.5
(iv) 30.94 ÷ 0.7
Answer
= (3094/100) ÷ (7/10)
= (3094/100) × (10/7)
= (3094 × 10)/ (100 × 7)
= (442 × 1)/ (10 × 1)
= 442/10
= 44.2
(v) 0.5 ÷ 0.25
Answer
= (5/10) ÷ (25/100)
= (5/10) × (100/25)
= (5 × 100)/ (10 × 25)
= (1 × 10)/ (1 × 5)
= 10/5
= 2
(vi) 7.75 ÷ 0.25
Answer
= (775/100) ÷ (25/100)
= (775/100) × (100/25)
= (775 × 100)/ (100 × 25)
= (155 × 1)/ (1 × 5)
= (31 × 1)/ (1 × 1)
= 31
(vii) 76.5 ÷ 0.15
Answer
= (765/10) ÷ (15/100)
= (765/10) × (100/15)
= (765 × 100)/ (10 × 15)
= (51 × 10)/ (1 × 1)
= 510
(viii) 37.8 ÷ 1.4
Answer
= (378/10) ÷ (14/10)
= (378/10) × (10/14)
= (378 × 10)/ (10 × 14)
= (27 × 1)/ (1 × 1)
= 27
(ix) 2.73 ÷ 1.3
Answer
= (273/100) ÷ (13/10)
= (273/100) × (10/13)
= (273 × 10)/ (100 × 13)
= (21 × 1)/ (10 × 1)
= 21/10
= 2.1
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?
Answer
Total distance covered by vehicle in 2.4 litres of petrol = 43.2 km
Distance covered in 1 litre of petrol = 43.2 ÷ 2.4
= (432/10) ÷ (24/10)
= (432/10) × (10/24)
= (432 × 10)/ (10 × 24)
= (36 × 1)/ (1 × 2)
= (18 × 1)/ (1 × 1)
= 18 km
∴ Total distance covered in 1 liter of petrol is 18 km.