Class 7 Maths Chapter 2 – Fractions and Decimals Exercise 2.5
1. Which is greater?
(i) 0.5 or 0.05
Solution:-
By comparing whole number, 0 = 0
By comparing the tenths place digit, 5 > 0
∴ 0.5 > 0.05
(ii) 0.7 or 0.5
Solution:-
By comparing whole number, 0 = 0
By comparing the tenths place digit, 7 > 5
∴ 0.7 > 0.5
(iii) 7 or 0.7
Solution:-
By comparing whole number, 7 > 0
∴ 7 > 0.7
(iv) 1.37 or 1.49
Solution:-
By comparing whole number, 1 = 1
By comparing the tenths place digit, 3 < 4
∴ 1.37 < 1.49
(v) 2.03 or 2.30
Solution:-
By comparing whole number, 2 = 2
By comparing the tenths place digit, 0 < 3
∴ 2.03 < 2.30
(vi) 0.8 or 0.88
Solution:-
By comparing whole number, 0 = 0
By comparing the tenths place digit, 8 = 8
By comparing the hundredths place digit, 0 < 8
∴ 0.8 < 0.88
2. Express as rupees as decimals:
(i) 7 paise
Solution:-
We know that,
= Rs 1 = 100 paise
= 1 paise = Rs (1/100)
∴ 7 paise = Rs (7/100)
= Rs 0.07
(ii) 7 rupees 7 paise
Solution:-
We know that,
= Rs 1 = 100 paise
= 1 paise = Rs (1/100)
∴ 7 rupees 7 paise = Rs 7 + Rs (7/100)
= Rs 7 + Rs 0.07
= Rs 7.07
(iii) 77 rupees 77 paise
Solution:-
We know that,
= Rs 1 = 100 paise
= 1 paise = Rs (1/100)
∴ 77 rupees 77 paise = Rs 77 + Rs (77/100)
= Rs 77 + Rs 0.77
= Rs 77.77
(iv) 50 paise
Solution:-
We know that,
= Rs 1 = 100 paise
= 1 paise = Rs (1/100)
∴ 50 paise = Rs (50/100)
= Rs 0.50
(v) 235 paise
Solution:-
We know that,
= Rs 1 = 100 paise
= 1 paise = Rs (1/100)
∴ 235 paise = Rs (235/100)
= Rs 2.35
3. (i) Express 5 cm in meter and kilometer
Solution:-
We know that,
= 1 meter = 100 cm
Then,
= 1 cm = (1/100) m
= 5 cm = (5/100)
= 0.05 m
Now,
= 1 km = 1000 m
Then,
= 1 m = (1/1000) km
= 0.05 m = (0.05/1000)
= 0. 00005 km
(i) Express 35 mm in cm, m and km
Solution:-
We know that,
= 1 cm = 10 mm
Then,
= 1 mm = (1/10) cm
= 35 mm = (35/10) cm
= 3.5 cm
And,
= 1 meter = 100 cm
Then,
= 1 cm = (1/100) m
= 3.5 cm = (3.5/100) m
= (35/1000) m
= 0.035 m
Now,
= 1 km = 1000 m
Then,
= 1 m = (1/1000) km
= 0.035 m = (0.035/1000)
= 0. 000035 km
4. Express in kg:
(i) 200 g
Solution:-
We know that,
= 1 kg = 1000 g
Then,
= 1 g = (1/1000) kg
= 200 g = (200/1000) kg
= (2/10)
= 0.2 kg
(ii) 3470 g
Solution:-
We know that,
= 1 kg = 1000 g
Then,
= 1 g = (1/1000) kg
= 3470 g = (3470/1000) kg
= (3470/100)
= 3.470 kg
(ii) 4 kg 8 g
Solution:-
We know that,
= 1 kg = 1000 g
Then,
= 1 g = (1/1000) kg
= 4 kg 8 g = 4 kg + (8/1000) kg
= 4 kg + 0.008
= 4.008 kg
5. Write the following decimal numbers in the expanded form:
(i) 20.03
Solution:-
We have,
20.03 = (2 × 10) + (0 × 1) + (0 × (1/10)) + (3 × (1/100))
(ii) 2.03
Solution:-
We have,
2.03 = (2 × 1) + (0 × (1/10)) + (3 × (1/100))
(iii) 200.03
Solution:-
We have,
200.03 = (2 × 100) + (0 × 10) + (0 × 1) + (0 × (1/10)) + (3 × (1/100))
(iv) 2.034
Solution:-
We have,
2.034 = (2 × 1) + (0 × (1/10)) + (3 × (1/100)) + (4 × (1/1000))
6. Write the place value of 2 in the following decimal numbers:
(i) 2.56
Solution:-
From the question, we observe that,
The place value of 2 in 2.56 is ones
(ii) 21.37
Solution:-
From the question, we observe that,
The place value of 2 in 21.37 is tens
(iii) 10.25
Solution:-
From the question, we observe that,
The place value of 2 in 10.25 is tenths.
(iv) 9.42
Solution:-
From the question, we observe that,
The place value of 2 in 9.42 is hundredth.
(v) 63.352
Solution:-
From the question, we observe that,
The place value of 2 in 63.352 is thousandth.
7. Dinesh went from place A to place B and from there to place C. A is 7.5 km from B and B is 12.7 km from C. Ayub went from place A to place D and from there to place C. D is 9.3 km from A and C is 11.8 km from D. Who travelled more and by how much?
Solution:-
From the question, it is given that,
Distance travelled by Dinesh = AB + BC
= 7.5 + 12.7
= 20.2 km
∴Dinesh travelled 20.2 km
Distance travelled by Ayub = AD + DC
= 9.3 + 11.8
= 21.1 km
∴Ayub travelled 21.1km
Clearly, Ayub travelled more distance by = (21.1 – 20.2)
= 0.9 km
∴Ayub travelled 0.9 km more than Dinesh.
8. Shyama bought 5 kg 300 g apples and 3 kg 250 g mangoes. Sarala bought 4 kg 800 g oranges and 4 kg 150 g bananas. Who bought more fruits?
Solution:-
From the question, it is given that,
Fruits bought by Shyama = 5 kg 300 g
= 5 kg + (300/1000) kg
= 5 kg + 0.3 kg
= 5.3 kg
Fruits bought by Sarala = 4 kg 800 g + 4 kg 150 g
= (4 + (800/1000)) + (4 + (150/1000))
= (4 + 0.8) kg + (4 + .150) kg
= 4.8 kg + 4.150kg
= 8.950 kg
So, Sarala bought more fruits.
9. How much less is 28 km than 42.6 km?
Solution:-
Now, we have to find the difference of 42.6 km and 28 km
42.6
-28.0
14.6
∴ 14.6 km less is 28 km than 42.6 km.