If two liquids of same volume but different densities $\rho_1$ and $\rho_2$ are mixed,then the density of the mixture is given by:

• A
  $\rho = \frac{\rho_1 + \rho_2}{2}$
• B
  $\rho = \frac{\rho_1 + \rho_2}{2\rho_1\rho_2}$
• C
  $\rho = \frac{2\rho_1\rho_2}{\rho_1 + \rho_2}$
• D
  $\rho = \frac{\rho_1\rho_2}{\rho_1 + \rho_2}$