Using the Voigt and Reuss models, calculate the elastic modulus of a collagen-hydroxyapatite composite for volume fractions of HA ranging from 0 to 1. Generate a plot with the elastic modulus plotted vs the volume fraction of HA. On the same graph, denote the elastic moduli for cortical bone, dentin, and enamel. Based on your graph, what would be the approximate volume fraction of HA for dentin and enamel if the Voigt model is assumed to be valid?