What is the effective density of the mixture of water and milk when
they are taken with same volumes ?

Explanation

When they are taken with same volume 'V' and masses are `m_(1) and m_(2)`
`"Volume of water V"=(m_(1))/(rho_(1))`
`" That is "m_(1)=Vrho_(1)`
And the volume of milk `V=(m_(2))/(rho_(2))`
`" That is "m_(2)=Vrho_(2)`
Total mass of water and milk is `m_(1)+m_(2)=Vrho_(1)+Vrho_(2)=V(rho_(1)+rho_(2))`
Total volume of water and milk is V + V = 2V
The effective density of the mixture
`(rho_("eff"))=("Total mass")/("Total volum")=(V(rho_(1)+rho_(2)))/(2V)=(1)/(2)(rho_(1)+rho_(2))`