Problema Solution
According to science, Earth is about 4.5 billion years old and written human history extends back about 10,000 years. Suppose you represent the entire history of Earth with a 100-meter-long timeline, with the birth of Earth on one end and today at the other end. What distance represents 1 billion years? How far from the end of the timeline does written human history begin?
Answer provided by our tutors
1 billion = 1,000,000,000 years = 10^9 years
10,000 years = 10^4 years
10^4 years are represented with a 100-meter-long timeline
10^9 years are represented with a x-meter-long timeline
10^4/100 = 10^9/x
x = 10^7 m
1 billion = 10^9 years are represented with a 10^7-meter-long timeline
4.5 billion = 4.5*10^9 years are represented with a 4.5*10^7-meter-long timeline
(4.5*10^7 - 100) meters from the start is where the written human history begins.