[tex]\displaystyle Se~da:\\ \\
V_1=200ml=0,0002m^3\\ \\
V_2=50cm^3=0,00005m^3\\ \\
\rho_1=1\frac g{cm^3}=1000\frac {kg}{m^3}\\ \\
\rho_2=0,9\frac g{cm^3}=900\frac{kg}{m^3}\\ \\
\rho=?\frac {kg}{m^3}\\ \\ \\[/tex]
[tex]\displaystyle Formule:\\ \\
\rho=\frac mV\\ \\
\rho=\frac{m_1+m_2}{V_1+V_2}\\ \\
\rho=\frac{\rho_1\times V_1+\rho_2\times V_2}{V_1+V_2}\\ \\ \\
Calcule:\\ \\
\rho=\frac{1000\times 0,0002+900\times 0,00005}{0,0002+0,00005}=980\frac{kg}{m^3}[/tex]
