Class 7 Chapter 2 – Fractions and Decimals Exercise 2.7
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.