Arock weighing 75.0g placed in a graduated cylinder displacing the volume from 31.4 ml to 36.5 ml what is density of the rock in grams/cubic centimeters?

ρ≅13.0⋅g⋅mL−1 = 13.0⋅g⋅cm−3

Density=MassPer unit Volume = 75.0⋅g(36.5−31.4)⋅mL =??g⋅mL−1

Note that 1⋅mL = 1⋅cm−3; these are equivalent units of volume; 
i.e. 1⋅cm3 = 1×(10−2⋅m)3=1×10−6⋅m3=10−3⋅L=1⋅mL.