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# Just trying to verify if my answers were correct

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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.

Jul 4, 2019

#1
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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.

Jul 4, 2019
#2
+111438
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In the first situation, the population density is given by :

[ 7.6 x 109 ]              7.6

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

[5.1 x 108 ]              5.1

In the second situation, we have

[7.6 x 10]                    7.6

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

[ 5.1 x 108 x .30]           5.1 x .3

Jul 4, 2019