9702_s22_qp_11 Question 15

In a large container in an oil refinery, three oils of different densities are mixed. No chemical activity occurs. 

The mixture consists of: 

1200 kg of oil of density 1100 kgm^–3 

1500 kg of oil of density 860 kgm^–3 

4000 kg of oil of density 910 kgm^–3. 

What is the density of the mixture? 

A 927 kgm^–3 

B 933 kgm^–3 

C 957 kgm^–3 

D 1045 kgm^–3

ANSWER: A

The Physics Behind

• Density of the mixture is equal to the combined masses over the total volume of the mixture.
• The total mass is 6700 kg.
• The total volume equivalent to each given mass can be calculated by dividing the given mass by the corresponding density.
• The total volume or the volume of the mixture, then, should be 7.23 m³.
• Now, the density is

6700 kg / 7.23 m³

927 kgm^–3