If the gasoline floats on the surface of the puddle, what does that tell you about how its density compares to that of water? Explain your answer.

It tells that gasoline is less dense than water, because according to Archimedes Law states that any body completely or partially submerged in a fluid is acted upon by an upward, or buoyant, force, the magnitude of which is equal to the weight of the fluid, displaced by the object. So, when gasoline is put in water, it floats, it means that the buoyancy force is greater than gasoline's weight. It means that the weight of the same volume of water is more than the weight of the same volume of gasoline. It means that water has more density.