Language, notation and formulas

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# 6.2 Another ‘billions’ solution

Pretend that you are the marker of another solution to the same problem. How would you mark Solution B?

## Example 16 Billions

You may think that you know what the word billion means but do you really have a feel for its size?

 (a) Write down one billion as a power of 10. [3] (b) Consider how far a billion centimetres (cm) is. Determine what one billion cm is in kilometres (km). How does it compare with the distance between Saturn and the Sun, which is 1427000 000 km? [5] (c) Now consider one billion seconds. Determine how long this is in years (round your answer to the nearest whole number). [7] (d) Finally, if there are 4 980 000 grains in 1 kilogram (kg) of sugar, show that one billion grains of sugar are approximately equivalent to 2 × 102 kg of sugar. [5]

## Sample Solution B to Example 16

• (a) 109

• (b) 109 ÷ 102 ÷ 103 = 104

• (c) 109 ÷ 60 ÷ 60 ÷ 365 = 761

• (d) = 4.980 × 106 ÷ 109 = 4.980 × 10−3

Click on ‘Reveal answer’ to see the tutor's marking.

MU120_4M6