Explanation:

Given info:

The length of recorded history for humankind is about 5000 years and the age of the Earth is 4.5 billion years that can be approximated as 5 billion years .

We know that 1 billion =109 years , therefore 5 billion years =5×109 years .

The expression for calculating the fraction of geological timescale represented by the recorded human history,

Fraction of timescale denoted by recorded human history =Length of recorded human historyAge of the Earth

Substitute 5000 years for the length of recorded human history and 5×109 years for the age of Earth in the above expression.

Fraction of timescale denoted by recorded human history =5000 years5×109 years=0.000001

The expression for calculating the percentage of the fraction denoted by recorded human history, Percentage of the fraction of timescale denoted by recorded human history =Fraction of human history×100

Substitute 0.000001 for the fraction of human history in the above expression.

Percentage of the fraction of timescale denoted by recorded human history =0.000001×100=0.000100