# Density word problems

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

### Problem

Hot air is less dense than cool air, so hot air will rise above cool air. Increasing the air temperature inside a hot air balloon makes it lighter than the surrounding air, so the balloon can lift up. The density of hot air is about 0, point, 25, space, k, g, slash, m, start superscript, 3, end superscript less than that of cool air, which means a cubic meter of hot air can lift about 0, point, 25, space, k, g.
What is the minimum volume of hot air needed to lift a hot air balloon carrying 500, space, k, g?
space, m, start superscript, 3, end superscript
space