please can I get some help with this question?

b) Calculate the density of a composite containing a polymer matrix with density equal to 1.25 g cm-3 and 60% w/w glass fibres with density equal to 2.50 g cm-3. Also, calculate the volume fraction of each component and explain why the measured density value is usually lower than the theoretical value. b) Calculate the density of a composite containing a polymer matrix with density equal to 1.25 g cm-3 and 60% w/w glass fibres with density equal to 2.50 g cm-3. Also, calculate the volume fraction of each component and explain why the measured density value is usually lower than the theoretical value