About 70% of earth is covered in water, making 30% of earth potentially habitable by humans. earth can be modeled as a sphere with diameter 12, 700 km. there are 7.1 billion people in the world. what is the population density of potentially habitable earth?

The population density is 47 people/km^2..

Step 1. Calculate the surface area of Earth.

d = 12 700 km; r = 6350 km

A = 4πr^2 = 4π × (6350 km)^2 = 5.067 × 10^8 km^2

Step 2. Calculate the habitable surface area.

Habitable area = 5.067 × 10^8 km^2 total × (30 km^2 habitable/100 km^2 total) = 1.520 × 10^8 km^2 habitable

Step 3. Calculate the population density

Population density = 7.1 × 10^9 people/1.520 × 10^8 km^2 = 47 people/km^2