The Earth's surface area is approximately 5.1 * 10^8 km^2 (2 s.f.) and its population is 7.6 * 10^9 (2 s.f.). Population density is the number of people per square kilometre. Determine the population density of the Earth assuming all the the surface is land habitable by humans.

About 30% of the Earth's surface is land, including Antarctica. Determine the population density of the Earth assuming that all the land is habitable, but not the oceans.

Guest Jul 4, 2019

#1**+1 **

Just divide:

[7.6 x 10^9] / [5.1 x 10^8] =~15 people per km^2 - human population density.

30% x [5.1 x 10^8] =1.53 x 10^8 Km^2 - the surface area of all the land.

[7.6 x 10^9] / [1.53 x 10^8] =~ 50 people per km^2 on all habitable land.

Guest Jul 4, 2019

#2**+1 **

In the first situation, the population density is given by :

[ 7.6 x 10^{9} ] 7.6

__________ = ____ x 10 ≈ 14.9 people / km^2

[5.1 x 10^{8} ] 5.1

In the second situation, we have

[7.6 x 10^{9 }] 7.6

______________ = ________ x 10 ≈ 49.7 people /km^2

[ 5.1 x 10^{8} x .30] 5.1 x .3

CPhill Jul 4, 2019