NCERT Solutions Class 7th Math Chapter – 2 Fractions and Decimals Exercise – 2.5

1. Find:

(i) 0.4 ÷ 2

Solution:

We have,
= (4/10) ÷ 2

Then,
= (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.
Then, = 0.2

(ii) 0.35 ÷ 5

Solution:

We have,
= (35/100) ÷ 5

Then,
= (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.Then,
= 0.07

(iii) 2.48 ÷ 4

Solution:

We have,
= (248/100) ÷ 4

Then,
= (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.
Then,
= 0.62

(iv) 65.4 ÷ 6

Solution:

We have,
= (654/10) ÷ 6

Then,
= (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.
Then,
= 10.9

(v) 651.2 ÷ 4

Solution:

We have,
= (6512/10) ÷ 4

Then,
= (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.
Then,
= 162.8

(vi) 14.49 ÷ 7

Solution:

We have,
= (1449/100) ÷ 7

Then,
= (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.
Then,
= 2.07

(vii) 3.96 ÷ 4

Solution:

We have,
= (396/100) ÷ 4

Then,
= (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.
Then,
= 0.99

(viii) 0.80 ÷ 5

Solution:

We have,
= (80/100) ÷ 5

Then,
= (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.
Then,
= 0.16

2. Find:

(i) 4.8 ÷ 10

Solution:

On dividing a decimal by 10, the decimal point is shifted to the left by one place.
We have,
= 4.8 ÷ 10
= (4.8/10)
= 0.48

(ii) 52.5 ÷ 10

Solution:

On dividing a decimal by 10, the decimal point is shifted to the left by one place.
We have,
= 52.5 ÷ 10
= (52.5/10)
= 5.25

(iii) 0.7 ÷ 10

Solution:

On dividing a decimal by 10, the decimal point is shifted to the left by one place.
We have,
= 0.7 ÷ 10
= (0.7/10)
= 0.07

(iv) 33.1 ÷ 10

Solution:

On dividing a decimal by 10, the decimal point is shifted to the left by one place.
We have,
= 33.1 ÷ 10
= (33.1/10)
= 3.31

(v) 272.23 ÷ 10

Solution:

On dividing a decimal by 10, the decimal point is shifted to the left by one place.
We have,
= 272.23 ÷ 10
= (272.23/10)
= 27.223

(vi) 0.56 ÷ 10

Solution:

On dividing a decimal by 10, the decimal point is shifted to the left by one place.
We have,
= 0.56 ÷ 10
= (0.56/10)
= 0.056

(vii) 3.97 ÷10

Solution:

On dividing a decimal by 10, the decimal point is shifted to the left by one place.
We have,
= 3.97 ÷ 10
= (3.97/10)
= 0.397

3. Find:

(i) 2.7 ÷ 100

Solution: 

On dividing a decimal by 100, the decimal point is shifted to the left by two places.
We have,
= 2.7 ÷ 100
= (2.7/100)
= 0.027

(ii) 0.3 ÷ 100

Solution:

On dividing a decimal by 100, the decimal point is shifted to the left by two places.
We have,
= 0.3 ÷ 100
= (0.3/100)
= 0.003

(iii) 0.78 ÷ 100

Solution:

On dividing a decimal by 100, the decimal point is shifted to the left by two places.
We have,
= 0.78 ÷ 100
= (0.78/100)
= 0.0078

(iv) 432.6 ÷ 100

Solution:

On dividing a decimal by 100, the decimal point is shifted to the left by two places.
We have,
= 432.6 ÷ 100
= (432.6/100)
= 4.326

(v) 23.6 ÷100

Solution:

On dividing a decimal by 100, the decimal point is shifted to the left by two places.
We have,
= 23.6 ÷ 100
= (23.6/100)
= 0.236

(vi) 98.53 ÷ 100

Solution:

On dividing a decimal by 100, the decimal point is shifted to the left by two places.
We have,
= 98.53 ÷ 100
= (98.53/100)
= 0.9853

4. Find:

(i) 7.9 ÷ 1000

Solution:

On dividing a decimal by 1000, the decimal point is shifted to the left by three places.
We have,
= 7.9 ÷ 1000
= (7.9/1000)
= 0.0079

(ii) 26.3 ÷ 1000

Solution:

On dividing a decimal by 1000, the decimal point is shifted to the left by three places.
We have,
= 26.3 ÷ 1000
= (26.3/1000)
= 0.0263

(iii) 38.53 ÷ 1000

Solution:

On dividing a decimal by 1000, the decimal point is shifted to the left by three places.
We have,
= 38.53 ÷ 1000
= (38.53/1000)
= 0.03853

(iv) 128.9 ÷ 1000

Solution:

On dividing a decimal by 1000, the decimal point is shifted to the left by three places.
We have,
= 128.9 ÷ 1000
= (128.9/1000)
= 0.1289

(v) 0.5 ÷ 1000

Solution:

On dividing a decimal by 1000, the decimal point is shifted to the left by three places.
We have,
= 0.5 ÷ 1000
= (0.5/1000)
= 0.0005

5. Find:

(i) 7 ÷ 3.5

Solution: We have,
= 7 ÷ (35/10)
= 7 × (10/35)
= 1 × (10/5)
= 2

(ii) 36 ÷ 0.2

Solution: We have,
= 36 ÷ (2/10)
= 36 × (10/2)
= 18 × 10
= 180

(iii) 3.25 ÷ 0.5

Solution: We have,
= (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

Solution: We have,
= (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

Solution: We have,
= (5/10) ÷ (25/100)
= (5/10) × (100/25)
= (5 × 100)/ (10 × 25)
= (1 × 10)/ (1 × 5)
= 10/5
= 2

(vi) 7.75 ÷ 0.25

Solution: We have,
= (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

Solution: We have,
= (765/10) ÷ (15/100)
= (765/10) × (100/15)
= (765 × 100)/ (10 × 15)
= (51 × 10)/ (1 × 1)
= 510

(viii) 37.8 ÷ 1.4

Solution: We have,
= (378/10) ÷ (14/10)
= (378/10) × (10/14)
= (378 × 10)/ (10 × 14)
= (27 × 1)/ (1 × 1)
= 27

(ix) 2.73 ÷ 1.3

Solution: We have,
= (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?

Solution:

From the question, it is given that,
Total distance covered by vehicle in 2.4 litres of petrol = 43.2 km

Then, 
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.