# Density word problems

Solve problems concerning real-world situations using your knowledge of volume, surface area, and density.
You might need: Calculator

### Problem

About 70, percent of earth is covered in water, making 30, percent of earth potentially habitable by humans. Earth can be modeled as a sphere with diameter 12, comma, 700, space, k, m. There are 7, point, 1 billion people in the world.
What is the population density of potentially habitable earth?
Please choose from one of the following options.