Answer:
To determine population density, you divide the population of a country by its land area.
For the greatest population density:
1. Ghana: Population = 18,339,000, Area = 237,533 square km
Population Density = 18,339,000 / 237,533 ≈ 77.2 people per square km
For the least population density:
1. U.S.: Population = 272,648,000, Area = 9,364,520 square km
Population Density = 272,648,000 / 9,364,520 ≈ 29.1 people per square km
So, Ghana has the greatest population density, and the U.S. has the least.