The mass and volume ratio is calculated by density using the following expression: D = m / V, where D is density, m is the mass and v is the volume. This question is related to proportionality between variables. A proportion is a value for the ratio of two numbers. Therefore, the proportion is linked to the fraction, where we have a numerator and a denominator. Thus, we have an equivalence ratio between two values. > For this is the water density (1 kg/liter).