Densities via rule of mixtures

Question 1

What is p(composite)?

Answer 1

= mass(composite)/volume(composite)

Question 2

What is p(composite) assuming 1g of sample if volume fractions are known?

Answer 2

= 1/[(Mfa/pa)+(Mfb/pb)+(Mfc/pc)]

~Mf: mass fraction

Question 3

What is p(composite) assuming 1cm^3 sample?

Answer 3

= Vfapa + Vfbpb + Vfc*pc

~ Vf: volume fraction