How to find the density of a mixture

Question

water and oil are mixed in the ratio of 3:5. Find the density of the mixture if the density of water is 1g/cm³ and the density of oil is 0.8g/cm³

Answer 1

Since density is defined as mass/volume, let us find the total mass and the total volume.

3 ml water x 1 g/ml = 3 g

5 ml oil x 0.8 g/ml = 4 g

Total mass = 3 g + 8 g = 7 g

Total volume = 3 ml + 5 ml = 8 ml

Density = 7 g / 8 ml = 0.875 g/ml (0.9 g/ml if you round to 1 sig. fig.)