Answer:
5.2 g/cm³
Step-by-step explanation:
Given a sculpture consisting of 2 cm³ at 4 g/cm³, 7 cm³ at 5 g/cm³, and 5 cm³ at 6 g/cm³, you want its average density.
The total mass of the sculpture is the sum of the masses of the components. Each of those is the product of its volume and density.
red sand: (2 cm³)(4 g/cm³) = 8 g
yellow sand: (7 cm³)(5 g/cm³) = 35 g
brown sand: (5 cm³)(6 g/cm³) = 30 g
The total mass of the sculpture is ...
total mass = 8 g + 35 g + 30 g = 73 g
The total volume of the sculpture is the sum of the volumes of its parts:
total volume = 2 cm³ +7 cm³ +5 cm³ = 14 cm³
The density is the ratio of mass to volume:
ρ = (total mass)/(total volume) = (73 g)/(14 cm³) = 73/14 g/cm³
= 5 3/14 g/cm³ ≈ 5.2 g/cm³
The average density of the sculpture is about 5.2 g/cm³.