Exercise 6.3
1. Express the following numbers in the standard form
(i) 3908.78
(ii) 5, 00, 00, 000
(iii) 3, 18, 65, 00, 000
(iv) 846 × 107
(v) 723 × 109
Solution:
(i) 3908.78 = 3.90878 × 103
After that, the decimal point is moved three places to the left
(ii) 5, 00, 00, 000 = 5, 00, 00, 000.00
= 5 × 107
After that, the decimal point is moved seven places to the left
(iii) 3, 18, 65, 00, 000 = 3, 18, 65, 00, 000.00
= 3.1865 × 109
After that, the decimal point is moved nine places to the left
(iv) 846 × 107 = 8.46 × 102 × 107
= 8.46 × 109
After that, the decimal point is moved two places to the left
(v) 723 × 109 = 7.23 × 102 × 109
= 7.23 × 1011
After that, the decimal point is moved two places to the left
2. Write the following numbers in the usual form
(i) 4.83 × 107
(ii) 3.21 × 105
(iii) 3.5 × 103
Solution:
(i) Given 4.83 × 107
4.83 × 107=483107-2 [After that the decimal point is moved two place to the right]
= 483×105
= 4, 83, 00, 000
(ii) Given 3.21 × 105
3.21 × 105 = 321×105[After that the decimal point is moved two place to the right]
= 321105
= 3, 21,000
(iii) Given 3.5 × 103
3.5×103=35×103-1 [After that the decimal point is moved one place to the right]
= 35×102
= 3,500
3. Express the numbers appearing in the following statements in the standard form
(i) The distance between the earth and the moon is 384,000,000 metres.
(ii) Diameter of the earth is 1, 27, 56,000 metres.
(iii) Diameter of the sun is 1, 400, 000, 000 metres.
(iv) The universe is estimated to be about 12,000,000,000 years old.
Solution:
(i) The distance between the earth and the moon is 3.84 × 108 metres.
After that, the decimal point is moved eight places to the left
(ii) Diameter of the earth is 1.2756 × 107 metres.
After that, the decimal point is moved seven places to the left
(ii) Diameter of the sun is 1.4 × 109 metres.
After that, the decimal point is moved nine places to the left
(iv) The universe is estimated to be about 1.2 × 1010 years old.
After that, the decimal point is moved ten places to the left