Decimal Fractions ICSE Class-7th Concise Selina Maths Solutions Chapter-4. We provide step by step Solutions of Exercise / lesson-4 Decimal Fractions for ICSE Class-7 Concise Selina Mathematics. Our Solutions contain all type Questions with Exe-4 A, Exe-4 B, Exe-4 C Exe-4 D , Exe-4 E and Exe-4 F to develop skill and confidence. Visit official Website CISCE for detail information about ICSE Board Class-7.
Decimal Fractions ICSE Class-7th Concise Selina Maths Solutions Chapter-4
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Exercise – 4 A
Decimal Fractions ICSE Class-7th Concise Selina
Question-1:-
Convert the following into fractions in their lowest terms :
(i) 3.75
(ii) 0.5
(iii) 2.04
(iv) 0.65
(v) 2.405
(vi) 0.085
(vii) 8.025
Answer-1:-
(i) 3.75
(ii) 0.5
= 5/10 =1/2
(iii) 2.04
(HCF of 204 and 100 = 4)
= 51/25
(iv) 0.65
(v) 2.405
(vi) 0.085
= 17/200
(vii) 8.025
= 321/40
Question-2:-
Convert into decimal fractions
Answer-2:-
(i)
= 14/5
= 2.8
(ii)
= 0.79
(iii)
= 0.0037
(iv)
= 7543/10000
= 0.7543
(v)
= 0.75
(vi)
= 48/5
= 9.6
(vii)
= 5.875
(viii)
= 5.875
Question-3:-
Write the number of decimal places in :
(i) 0.4762
(ii) 7.00349
(iii) 8235.403
(iv) 35.4
(v) 2.608
(vi) 0.000879
Answer-3:-
(i) Four
(ii) five
(iii) three
(iv) one
(v) three
(vi) six
Question-4:-
Write the following decimals as word statements :
(i) 0.4,0.9,0.1
(ii) 1.9, 4.4, 7.5
(iii) 0.02, 0.56, 13.06
(iv) 0.005,0.207, 111.519
(v) 0.8, 0.08, 0.008, 0.0008
(vi)256.1, 10.22, 0.634
Answer-4:-
(i) 0.4 – zero point four
0.9 – zero point nine
0.1 – zero point one
(ii) 1.9 – one point nine
4.4 – four point four
7.5 – seven point five
(iii) 0.02 – zero point zero two
0.56 – zero point five six
13.06 – thirteen point zero six
(iv) 0.005 – zero point zero zero five
0.207 – zero point two zero seven
111.519 – one hundred eleven point five one nine
(v) 0.8 – zero point eight
0.08 – zero point zero zero eight
0.008 – zero point zero zero zero eight
0.0008 – zero point zero zero zero zero eight
(vi) 256.1 – two hundred fifty six point one
10.22 – ten point two two
0.634 – zero point six three four
Question-5:-
Convert the given fractions into like fractions:
(i) 0.5,3.62,43.987 and 232.0037
(ii) 215.78, 33.0006, 530.3 and 0.03569
Answer-5:-
(i) 0.5000
3.6200
43.9870
232.0037
(ii) 215.78000
33.00060
530.30000
0.03569
Exercise – 4 B
Selina solutions Decimal Fractions for ICSE Class-7th
Question-1:-
Add:
(i) 0.5 and 0.37
(ii) 3.8 and 8.7
(iii) 0.02, 0.008 and 0.309
(iv) 0. 4136, 0. 3195 and 0.52
(v) 9.25, 3.4 and 6.666
(vi) 3.007, 0.587 and 18.341
(vii) 0.2, 0.02 and 2.0002
(viii) 6. 08, 60.8, 0.608 and 0.0608
(ix) 29.03, 0.0003, 0.3 and 7.2
(x) 3.4, 2.025, 9.36 and 3.6221
Answer-1:-
(i) 0.5 and 0.37
= 0.5 + 0.37 = 0.87
(ii) 3.8 and 8.7
= 3.8 + 8.7 = 12.5
(iii) 0.02, 0.008 and 0.309
= 0.02 + 0.008 + 0.309 = 0.337
(iv) 0. 4136, 0. 3195 and 0.52
= 0. 4136 + 0. 3195 + 0.52 = 1.2531
(v) 9.25, 3.4 and 6.666
= 9.25 + 3.4 + 6.666 = 19.316
(vi) 3.007, 0.587 and 18.341
= 3.007 + 0.587 + 18.341 = 21.935
(vii) 0.2, 0.02 and 2.0002
= 0.2 + 0.02 + 2.0002 = 2.2202
(viii) 6. 08, 60.8, 0.608 and 0.0608
= 6.08 + 60.8 + 0.608 + 0.0608 = 67.5488
(ix) 29.03, 0.0003, 0.3 and 7.2
= 29.03 + 0.0003 + 0.3 + 7.2 = 36.5303
(x) 3.4, 2.025, 9.36 and 3.6221
= 3.4 + 2.025 + 9.36 + 3.6221 = 18.4071
Question-2:-
Subtract the first! number from the second :
(i) 5.4, 9.8
(ii) 0.16, 4.3
(iii) 0.82, 8.6
(v) 2.237, 9.425
(vi) 41 .03, 59.46
(vii) 3.92. 26.86
(viii) 4.73, 8.5
(ix) 12.63, 36.2
(x) 0.845, 3.71
Answer-2:-
(i) 5.4, 9.8
4.30 – 0.16
= 4.14
(ii) 0.16, 4.3
4.30 – 0.16
= 4.14
(iii) 0.82, 8.6
8.60 – 0.82
= 7.78
(iv) 0.07, 8.43
8.43 – 0.07
= 8.36
(v) 2.237, 9.425
9.425 – 2.237
= 7.188
(vi) 41 .03, 59.46
59.46 – 41.03
= 18.43
(vii) 3.92. 26.86
26.86 – 3.92
= 22.94
(viii) 4.73, 8.5
8.50 – 4.73
= 3.77
(ix) 12.63, 36.2
36.20 – 12.63
= 23.57
(x) 0.845, 3.71
3.710 – 0.845
= 2.865
Question-3:-
Simplify :
(i) 28.796 -13.42 – 2.555
(ii) 93.354 – 62.82 – 13.045
(iii) 36 – 18.59 – 3.2
(iv) 86 + 16.95 – 3.0042
(v) 32.8 – 13 – 10.725 +3.517
(vi) 4000 – 30.51 – 753.101 – 69.43
(vii) 0.1835 + 163.2005 – 25.9 – 100
(viii) 38.00 – 30 + 200.200 – 0.230
(ix) 555.555 + 55.555 – 5.55 – 0.555
Answer-3:-
(i) 28.796 -13.42 – 2.555
= 28.796 – (13.42 – 2.555)
= 28.796 – 15.975
= 12.821
(ii) 93.354 – 62.82 – 13.045
= 28.796 – (13.42 – 2.555)
= 28.796 – 15.975
= 12.821
(iii) 36 – 18.59 – 3.2
= 36 – (18.59 + 3.2)
= 36 – (21.79)
= 14.21
(iv) 86 + 16.95 – 3.0042
= 86.00 + 16.95
= 102.95 – 3.0042
= 99.9458
(v) 32.8 – 13 – 10.725 +3.517
= (32.8 + 3.517) – (13 + 10.725)
= 36.317 – 23.725
= 12.592
(vi) 4000 – 30.51 – 753.101 – 69.43
= 4000 – (30.51 + 753.101 + 69.43)
= 4000 – 853.041
= 3146.959
(vii) 0.1835 + 163.2005 – 25.9 – 100
= (0.1835 + 163.2005) – (25.9 + 100)
= 163.3840 – 125.9
= 37.484
(viii) 38.00 – 30 + 200.200 – 0.230
= (38.00 + 200.200) – (30 + 0.230)
= 238.200 – 30.230
= 207.970
= 207.97
(ix) 555.555 + 55.555 – 5.55 – 0.555
= (555.555 + 55.555) – (5.55 + 0.555)
Question-4:-
Find the difference between 6.85 and 0.685.
Answer-4:-
= 6.85 – 0.685
= 6.165
Question-5:-
Take out the sum of 19.38 and 56.025 then subtract it from 200. 111.
Answer-5:-
Sum of 19.38 + 56.025
= 75.405
Difference of 200.111 and 75.405
= 200.111 – 75.405
= 124.706
Question-6:-
Add 13.95 and 1.003 ; and from the result, subtract the sum of 2.794 and 6.2.
Answer-6:-
Sum of 13.95 and 1.003
= 13.95 + 1.003
= 14.953
Sum of 2.794 and 6.2
= 2.794 + 6.2
= 8.994
Difference of 14.953 and 8.994
= 14.953 – 8.994
= 5.959
Question-7:-
What should be added to 39.587 to give 80.375 ?
Answer-7:-
Sum = 80.375
Given number = 39.589
∴ The number which is to be added
= 80.375 – 39.587
= 40.788
Question-8:-
What should be subtracted from 100 to give 19.29?
Answer-8:-
Sum = 100
The number = 19.29
∴ The number which is to be subtracted
= 100 – 19.29
= 80.71
Question-9:-
What is the excess of 584.29 over 213.95 ?
Answer-9:-
Total = 584.29
Given number = 213.95
Required difference = 584.29 – 213.95
= 370.34
Question-10:-
Evaluate:
(i) (5.4 – 0.8) + (2.97 -1.462)
(ii) (6.25 + 0.36) -(17.2 – 8.97)
(iii) 9.004 + (3 -2.462)
(iv) 879.4 – (87.94 – 8 .794)
Answer-10:-
(i)
(5.4 – 0.8) + (2.97 -1.462)
= 4.6 + 1.508
= 6.108
(ii)
(6.25 + 0.36) -(17.2 – 8.97)
= 6.61 – 8.23
= – 1.62
(iii)
9.001 + (3 – 2.462)
= 9.004 + 0.538
= 9.542
(iv)
879.4 – (87.94 – 8 .794)
= 879.4 – 79.146
= 800.254
Question-11:-
What is the excess of 75 over 48.29?
Answer-11:-
Excess of 75 over 48.29
75.00
– 48.29
26.71
∴ Excess of 75 over 48.29 is 26.71
Question 12.
If A = 237.98 and B = 83.47.
Find :
(i) A – B
(ii) B – A.
Answer-12:-
(i) A – B
A = 237.98
B = 83.47
A – B = 237.98 – 83.47
= 154.51
(ii) B – A
= 83.47 – 237.98
= – 154.51
Question-13:-
The cost of one kg of sugar increases from ?28.47 to T32.65. Find the increase in cost.
Answer-13:-
Initial cost of sugar = ₹ 28.47
Increase cost of sugar = ₹ 32.65
∴ Increase of sugar in cost = ₹ 5.18
Exercise – 4 C
Decimal Fractions ICSE Class-7th Mathematics
Question-1:-
Multiply:
(i) 0.87 by 10
(ii) 2.948 by 100
(iii) 6.4 by 1000
(iv) 5.8 by 4
(v) 16.32 by 28
(vi) 5. 037 by 8
(vii) 4.6 by 2.1
(viii) 0.568 by 6.4
Answer-1:-
(i) 0.87 by 10
= 0.87 × 10 = 8.7
(ii) 2.948 by 100
= 2.948 × 100 = 294.8
(iii) 6.4 by 1000
= 6.4 × 1000 = 6400
(iv) 5.8 by 4
= 5.8 × 4 = 23.2
(v) 16.32 by 28
= 16.32 × 28 = 456.96
(vi) 5. 037 by 8
= 5.037 × 8 = 40.296
(vi) 4.6 by 2.1
= 4.6 × 2.1 = 9.66
(viii) 0.568 by 6.4
= 0.568 × 6.4 = 3.6352
Question-2:-
Multiply each number by 10, 100, 1000 :
(i) 0.5
(ii) 0.112
(iii) 4.8
(iv) 0.0359
(v) 16.27
(vi) 234.8
Answer-2:-
(i)
0.5 x 10 = 5,
0.5 x 100 = 50,
0.5 x 1000 = 500
(ii)
0.112 x 10= 1.12,
0.112 x 100 = 11.2,
0.112 x 1000= 112
(iii)
4.8 x 10 = 48,
4.8 x 100 = 480,
4.8 x 1000 = 4800
(iv)
0.0359 x 10 = 0.359,
0.0359 x 100 = 3.59,
0.0359 x 1000 = 35.9
(v)
16.27 x 10 = 162.7,
16.27 x 100 = 1627,
16.27 x 1000= 16270
(vi)
234.8 x 10 = 2348,
234.8 x 100 = 23480,
234.8 x 1000 = 234800
Question-3:-
Evaluate:
(i) 5.897 x 2.3
(ii) 0.894 x 87
(iii) 0.01 x 0.001
(iv) 0.84 x 2.2 x 4
(v) 4.75 x 0.08 x 3
(vi) 2.4 x 3.5 x 4.8
(vii) 0.8 x 1.2 x 0.25
(viii) 0.3 x 0.03 x 0.003
(ix) 12.003 x (0.2)5
Answer-3:-
(i)
5.897 × 2.3
= 13.5631
(ii)
0.894 × 87
= 77.778
(iii)
0.01 × 0.001
= 0.00001
(iv)
0.84 × 2.2 × 4 = 0.84
=0.84 × 8.8
= 7.392
(v)
4.75 × 0.08 × 3 = 4.75 × 0.08 × 3
= 4.75 × 0.24
= 1.1400
= 1.14
(vi)
2.4 × 3.5 × 4.8 = 8.40 × 4.8
= 8.4 × 4.8
= 40.32
(vii)
0.8 × 1.2 × 0.25 = 0.96 × 0.25
= 0.2400
= 0.24
(viii)
0.3 × 0.03 × 0.003 = 0.009 × 0.003
= 0.000027
= 0.24
(ix)
12.003 × (0.2)5
= 12.003 × 0.2 × 0.2 × 0.2 × 0.2 × 0.2
= 12.003 × 0.00032 = 0.00384096
Question-4:-
Divide :
(i) 54.9 by 10
(ii) 7.8 by 100
(iii) 324.76 by 1000
(iv) 12.8 by 4
(v) 27.918 by 9
(vi) 4.672 by 8
(vii) 4.32 by 1.2
(viii) 7.644 by 1.4
(ix) 4.8432 by 0.08
Answer-4:-
(i)
= 54.9 ÷ 10
= 5.49
(ii)
= 7.8 ÷ 100
= 0.078
(iii)
= 324.76 ÷ 1000
= 0.32476
(iv)
= 12.8 ÷ 4
= 3.2
(v)
= 27.918 ÷ 9
= 3.102
(vi)
= 4.672 ÷ 8
= 0.584
(vii)
= 4.32 ÷ 1.20
= 432 ÷ 120
= 3.6
(viii)
= 7.644 ÷ 1.400
= 7644 ÷ 1400
= 5.46
(ix)
= 4.8432 ÷ 0.0800
= 48432 ÷ 800
= 60.54
Question-5:-
Divide each of the given numbers by 10, 100, 1000 and 10000
(i) 2.1
(ii) 8.64
(iii) 5-01
(iv) 0.0906
(v) 0.125
(vi) 111.11
(vii) 0.848 x 3
(viii)4.906 x (0.2) ²
(ix) (1.2)² x(0.9)²
Answer-5:-
(i)
2.1 ÷ 10 = 0.21,
2.1 ÷ 100 = 0.021,
2.1 ÷ 1000 = 0.0021
and
2.1 ÷10000 = 0.00021
(ii)
8.64 ÷ 10 = 0.864,
8.64 ÷ 100 = 0.0864,
8.64 ÷ 1000 = 0.00864
and
8.64 ÷ 10000 = 0.000864
(iii)
5.01 ÷ 10 = 0.501,
5.01 ÷ 100 = 0.0501,
5.01 ÷1000 = 0.00501,
5.01 ÷ 10000 = 0.000501
(iv)
0.0906 ÷ 10 = 0.00906,
0.0906 ÷ 100 = 0.000906,
0.0906 ÷ 1000 = 0.0090906,
0.0906 ÷ 10000 = 0.00000906
(v)
0.125 Now 0.125 + 10 = 0.0125,
0.125 ÷ 100 = 0-00125,
0.125 ÷1000 = 0.000125,
0.125 ÷ 10000 = 0.0000125
(vi)
111.11÷ 10= 11.111,
111.11÷ 100 = 1.1111,
111.11 ÷ 1000 = 0.11111,
111.11 ÷ 10000 = 0.011111
(vii)
0.848 x 3 = 2.544 ,
Now 2.544 ÷ 10 = 0.2544,
2.544 ÷ 100 = 0-02544,
2-544 ÷ 1000 = 0-002544,
2-544 ÷ 10000 = 0-0002544
(viii)
0.848 x 3 = 2.544 ,
Now 2.544 ÷ 10 = 0.2544,
2.544 ÷ 100 = 0-02544,
2-544 ÷ 1000 = 0-002544,
2-544 ÷ 10000 = 0-0002544
(ix)
(1.2)² x (0.9)²
= 1.2 x 1.2 x 0.9 x 0.9
= 1.44 x 0.81
= 1.1664
Now
1 .1664 + 10 = 0.11664,
1.1664 ÷ 100 = 0.011664,
1.1664 ÷ 1000 = 0.0011664,
1.1664 ÷ 10000 = 0.00011664
Question-6:-
Evaluate :
(i) 9.75 + 5
(ii) 4.4064 + 4
(iii) 27.69 + 30
(iv) 19.25 + 25
(v) 20.64+ 16
(vi) 3.204 + 9
(vii) 0.125 + 25
(viii) 0.14616 + 72
(ix) 0.6227+ 1300
(x) 257.894+ 0-169
(xi) 6.3 + (0.3)²
Answer-6:-
(i)
9.75 ÷ 5
= 1.95
(ii)
4.4064 ÷ 4
= 1.1016
(iii)
27.69 ÷ 30
= 0.923
(iv)
19.25 ÷ 25
= 0.77
(v)
20.64 ÷ 16
= 1.29
(vi)
3.204 ÷ 9
= 0.356
(vii)
0.125 ÷ 25
= 0.005
(Viii)
0.14616 ÷ 72
= 0.00203
(ix)
0.6227 ÷ 1300
= 0.000479
(x)
= 257894 ÷ 169
= 1526
(xi)
= 6.3 ÷ (0.3 × 0.3)
= 6.3 ÷ (0.09)
= 630 ÷ 09
= 630 ÷ 9
= 70
Question-7:-
Evaluate:
(i) 4.3 x 0.52 x 0.3
(ii) 3.2 x 2.5 x 0.7
(iii) 0.8 x 1.5 x 0.6
(iv) 0.3 x 0.3 x 0.3
(v) 1.2 x 1.2 x 0.4
(vi) 0.4 x 0.04 x 0.004
(vii) 0.5 x 0.6 x 0.7
(Viii) 0.5 x 0.06 x 0.007
Answer-7:-
(i)
4.3 x 0.52 x 0.3
= 0.6708
(ii)
3.2 x 2.5 x 0.7
= 5.600 or 5.6
(iii)
0.8 x 1.5 x 0.6
= 0.720 or 0.72
(iv)
0.3 x 0.3 x 0.3
= 0.027
(v)
1.2 x 1.2 x 0.4
= 0.576
(vi)
0.4 x 0.04 x 0.004
= 0.000064
(vii)
0.5 x 0.6 x 0.7
= 0.210 or 0.21
(viii)
0.5 x 0.06 x 0.007
= 0.00021
Question-8:-
Evaluate:
(i) (0.9)²
(ii) (0.6)² x 0.5
(iii) 0.3 x (0.5)²
(iv) (0.4)³
(v) (0.2)3 x 5
(vi) (0.2)3 x 0.05
Answer-8:-
(i)
(0.9)²
⇒ 0.9 x 0.9 = 0.81
(ii)
(0.6)² x 0.5
⇒ 0.6 x 0.6 x 0.5
⇒ 0.36 x 0.5 = 0.180 or 0.18
(iii)
0.3 x (0.5)2
⇒ 0.3 x 0.5 x 0.5
⇒ 0.3 x 0.25 = 0.075
(iv)
(0.4)3
⇒ 0.4 x 0.4 x 0.4
⇒ 0.16 x 0.4 = 0.064
(v)
(0.2)3 x 5
⇒ 0.2 x 0.2 x 0.2 x 5
⇒ 0.08 x 5 = 0.40 or 0.4
(vi)
(0.2)3 x 0.05
⇒ 0.2 x 0.2 x 0.2 x 0.05
⇒ 0.008 x 0.05 = 0.00040
Question-9:-
Find the cost of 36.75 kg wheat at the rate of ₹12.80 per kg.
Answer-9:-
Total weight of wheat = 36.75 kg
Cost of 1 kg of wheat = Rs. 12.80
∴ Cost of 36.75 kg of wheat
= 36.75 × 12.80
= Rs. 470.40
Question-10:-
The cost of a pen is ₹56.15. Find the cost of 16 such pens.
Answer-10:-
Total weight of wheat = 36.75 kg
Cost of 1 kg of wheat = Rs. 12.80
∴ Cost of 36.75 kg of wheat
= 36.75 × 12.80
= Rs. 470.40
Question-11:-
Evaluate:
(i) 0.0072 ÷ 0.06
(ii) 0.621 ÷ 0.3
(iii) 0.0532 ÷ 0.005
(iv) 0.01162 ÷ 0.14
(v) (7.5 x 40.4) ÷ 25
(vi) 2.1 ÷ (0.1 x 0.1)
Answer-11:-
(i) 0.0072 ÷ 0.06
(ii) 0.621 ÷ 0.3
(iii) 0.0532 ÷ 0.005
(iv) 0.01162 ÷ 0.14
(v) (7.5 x 40.4) ÷ 25
= 303/25
=12.12
(vi) 2.1 ÷ (0.1 x 0.1)
=210/1
=210
Question-12:-
Fifteen identical articles weigh 31.50 kg. Find the weight of each article.
Answer-12:-
Weight of 15 articles = 31.50 kg
∴ Weight of one article
= 31.50- 15
= 2.1 kg
Question-13:-
The product of two numbers is 211.2. If one of these two numbers is 16.5, find the other number.
Answer-13:-
The product of two numbers = 211.2
One number = 16.5
∴ Second number = 211.2 ÷ 16.5
Question-14:-
One dozen identical articles cost ₹45.96. Find the cost of each article.
Answer-14:-
Weight of one dozen articles = ₹45.96
One dozen = 12
∴ Cost of one article = 45.96 + 12
= ₹3.83
Exe-4 D
Selina Concise Maths Solutions for ICSE Class-7
Question-1:-
Find whether the given division forms a terminating decimal or a non-terminating decimal:
(i) 3 ÷ 8
(ii)8 ÷ 3
(iii) 6÷ 5
(iv) 5 ÷ 6
(v) 12.5 ÷ 4
(vi) 23 ÷ 0.7
(vii) 42 ÷ 9
(viii) 0.56÷ 0.11
Answer-1:-
(i) 3 ÷ 8
3 ÷ 8 = 0.375
Therefore it is terminating decimal.
(ii) 8 ÷ 3
8 ÷ 3 = 2.666…
Therefore it is non – terminating decimal.
(iii) 6÷ 5
6 ÷ 5 = 1.2
Therefore it is terminating decimal.
(iv) 5 ÷ 6
5 ÷ 6 = 0.8333……
Therefore it is non – terminating decimal.
(v) 12.5 ÷ 4
12.5 ÷ 4 = 3.125
Therefore it is terminating decimal.
(vi) 23 ÷ 0.7
23 ÷ 0.7 = 230 ÷ 7 = 32.8571428….
Therefore it is non – terminating decimal.
(vii) 42 ÷ 9
42 ÷ 9 = 4.666…
Therefore it is non – terminating decimal.
(viii) 0.56÷ 0.11
0.56 ÷ 0.11 = 56 ÷ 11 = 5.0909….
Therefore it is non – terminating decimal.
Question-2:-
Express as recurring decimals :
Answer-2:-
(i)
(ii)
(iii)
5/6 = 0.8333….
=0.83¯
(iv)
2/13 = 0.153846153846
= 0.153846
(v)
1/9 = 0.1111…
.=0.1¯
(vi)
17/90 = 0.1888…
.=0.18¯
(vii)
5/18 = 0.2777…
= 0.27¯
(viii)
7/12 = 0.58333….
=0.583¯
Question-3:-
Convert into vulgar fraction :
(i) 0.
(ii) 0.
(iii) 4.
(iv) 23.
Answer-3:-
(i)
(ii)
(iii)
(iv)
Question-4:-
Convert into vulgar fraction :
(i) 0.
(ii) 2.
(iii) 1.
(iv) 5.
Answer-4:-
(i)
(ii)
(iii)
(iv)
Question-5:-
Convert into vulgar fraction :
(i) 0 0.3
(ii) 0.2
(iii) 0.68
(iv) 0.4
Answer-5:-
(i)
(ii)
(iii)
(iv)
Exercise- 4 E
Decimal Fractions ICSE Class-7th Mathematics
Question-1:-
Round off:
(i) 0 .07, 0.112, 3.59, 9.489 to the nearest tenths.
(ii) 0.627, 100.479, 0 065 and 0.024 to the nearest hundredths.
(iii) 4.83,0.86,451 .943 and 9.08 to the nearest whole number.
Answer-1:-
(i)
0.07 = 0.1,
0.112 = 0.1
3.59 = 3.6,
9.489 = 9.5
(ii)
0.627 = 0.63,
100.479 = 100.48
0.065 = 0.07,
0.024 = 0.02
(iii)
4.83 = 5,
0.86= 1,
451.943 = 452
9.08 = 9
Question-2:-
Simplify, and write your answers correct to the nearest hundredths :
(i) 18 .35 x 1.2
(ii) 62.89 x 0.02
Answer-2:-
(i)
18 .35 x 1.2 = 22.02
(ii)
62.89 x 0.02 = 1.2578 = 1.26
Question-3:-
Write the number of significant figures (digits) in:
(i) 35.06
(ii) 0.35
(iii) 7.0068
(iv) 19 .0
(v) 0.0062
(vi) 0 4.2 x 0.6
(vii) 0.08 x 25
(viii) 3.6 ÷ 0.12 .
Answer-3:-
(i) 35.06
significant figures i.e. digits are 4
(ii) 0.35
significant figures are 2.
(iii) 7.0068
significant figures are 5
(iv) 19 .0
significant figures are 3
(v) 0.0062
significant figures are 2.
(vi) 0 4.2 x 0.6
2.52, significant figure are 3
(vii) 0.08 x 25
2.00 = 2 significant figure is 1.
(viii) 3.6 ÷ 0.12 .
360 ÷ 12 = 30
significant figure are 2.
Question-4:-
Write :
(i) 35.869,0 008426,4.952 and 382.7, correct lo three significant figures.
(ii) 60.974. 2.8753, 0.001789 and 400.04, correct to four significant figures.
(iii) 14.29462, 19.2, 46356.82 and 69, correct to five significant figures.
Answer-4:-
(i)
Correct to three significant figures are
35.869 → 35.9
0.008426 →0.00843
4.952→ 4.95
382.7 →383
(ii)
Correct to four significant figures
60.974 →60.97
2.8753 → 2.875
0.001789 → 0.001789
400.04 → 400.0
(iii)
Correct to five significant figures
14.29462→ 14.295
19.2 → 19.200
46356.82 →46357
69 → 69.000
Exercise 4 F
Decimal Fractions ICSE Class-7th Mathematics
Question-1:-
The weight of an object is 3 .06 kg. Find the total weight of 48 similar objects.
Answer-1:-
Weight of one object = 3.06 kg
∴ Weight of 48 object = 3.06 × 48 = 146.88 kg
3.06
× 48
2448,
12240
16688
Question-2:-
Find die cost of 17.5 m cloth at the rate of Rs. 112.50 per metre.
Answer-2:-
Cost of 1 meter cloth = Rs. 112.50
∴ Cost of 17.5 m cloth
= Rs. 112.50 × 17.5
= Rs. 1968.750
= 1968.75
112.50
× 17.5
56250
787500
1125000
16688
Question-3:-
One kilogram of oil costs Rs. 73.40. Find the cost of 9.75 kilogram of the oil.
Answer-3:-
Cost of 1 kg oil = Rs. 73.40
∴ Cost of 9.75 kg oil = Rs. 73.40 × 9.75
= Rs. 715.6500
= Rs. 715.65
73.40
× 9.75
36700
513800
6606000
7156500
Question-4:-
Total weight of 8 identical objects is 51.2 kg. Find the weight of each object.
Answer-4:-
Weight of 8 objects = 51.2 kg
∴ Weight of 1 object = 51.2 ÷ 8 kg = 6.4 kg
Question-5:-
18.5 m of cloth costs Rs. 666. Find the cost of 3.8 m cloth.
Answer-5:-
Cost of 18.5 m cloth = Rs. 666
Cost of 1 m cloth = Rs. 666 ÷18.5 and cost of 3.8 m cloth
= Rs. (666 ÷18.5) x 3.8 = Rs. (6660 ÷ 185) x 3.8
= Rs. 36 x 3.8 = Rs. 136.80
36
185) 6660
555
1110
1110
xxx
Question-6:-
Find die value of:
(i) 0.5 of Rs. 7.60 + 1.62 of Rs. 30
(ii) 2.3 of 7.3 kg + 0.9 of 0.48 kg
(iii) 6.25 of 8.4 – 4.7 of 3.24
(iv) 0.98 of 235 – 0 .09 of 3.2
Answer-6:-
(i) 0.5 of Rs. 7.60 + 1.62 of Rs. 30
= Rs. 3.80 + Rs. 48.60
= Rs. 52.40
(ii) 2.3 of 7.3 kg + 0.9 of 0.48 kg
= 16.79 kg + 0.432 kg
= 17.222 kg
(iii) 6.25 of 8.4 – 4.7 of 3.24
= 52.500 – 15.228
= 37.272
(iv) 0.98 of 235 – 0 .09 of 3.2
= 230.30 – 0.288
= 230.012
= 230.300
Question 7.
Evaluate:
(i) 5.6 – 1 .5 of 3.4
(ii) 4.8 ÷ 0.04 of 5
(iii) 0.72 of 80 + 0.2
(iv) 0.72 ÷ 80 of 0.2
(v) 6.45 + (3.9 – 1.75)
(vi) 0.12 of(0.104 – 0.02)+ 0.36 x 0.5
Answer-7:-
(i) 5.6 – 1 .5 of 3.4
3.4
× 1.5
170
340
5.10
= 5.6 – 5.1 = 0.5
(ii) 4.8 ÷ 0.04 of 5
= 4.8 ÷ 0.20
= 4.8 ÷ 0.2
= 48 ÷ 2
= 24
(iii) 0.72 of 80 + 0.2
= 57.60 ÷ 0.2
= 57.6 ÷ 0.2
=576 ÷ 2
= 288
(v) 6.45 + (3.9 – 1.75)
= 6.45 ÷ (3.90 – 1.75)
= 6.45 ÷ 2.15
= 645 ÷ 215
= 3
(vi) 0.12 of(0.104 – 0.02)+ 0.36 x 0.5
= 0.12 of 0.084 + 0.36 × 0.5
= 0.01008 + 0.180
= 0.19008
— End of Decimal Fractions Solutions :–
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