Ranks the objects from most to least dense : X,Z,Y,W
Further explanation
Given
Object W : m=16 g, V=84 cm³
Object X : m=12 g, V= 5 cm³
Object Y : m=4 g, V= 6 cm³
Object Z : m=408 g g, V= 216 cm³
Required
Density
Solution
Density formula:

ρ = density
m = mass
v = volume
1. Object W

2. Object X

3. Object Y

4. Object Z

From most to least dense : X,Z,Y,W