Question

The Earth is 4.6 billion years old, but human civilization (the building of cities) began only about 10,000 years ago. If you represent the history of Earth with a line one mile long (63,360 inches), how long must the line be to represent the history of human civilization?

Answer 1

0.13774 inches ( approx ).

Explanation:

Given,

The age of earth = 4.6 billion years = 4600000000 years,

The represented age of earth = 63,360 inches,

That is, scale factor in representation of age

`=\frac{\text{Represented age}}{\text{Actual age}}`

`=( 63,360)/(4600000000)`

Now, the age of human civilization = 10000 years,

Thus, the represented age of human civilization = actual age × scale factor

`=10000* ( 63,360)/(4600000000)`

`=(633600000)/(4600000000)`

`=0.137739130435`

`\approx 0.13774\text{ inches}`