## Basic College Mathematics (10th Edition)

XXS: $1\frac{1}{2}$ inches XS: $\frac{3}{4}$ inch S: $\frac{3}{4}$ inch M: $\frac{7}{8}$ inch L: $\frac{3}{4}$ inch
We find the differences in head size for each order size: XXS: $18-16.5=17\frac{2}{2}-16\frac{1}{2}=1\frac{1}{2}$ inches XS: $19-18.25=18\frac{4}{4}-18\frac{1}{4}=\frac{3}{4}$ inch S: $20-19.25=19\frac{4}{4}-19\frac{1}{4}=\frac{3}{4}$ inch M: $21\frac{1}{8}-20\frac{1}{4}=20\frac{9}{8}-20\frac{2}{8}=\frac{7}{8}$ inch L: $22\frac{1}{4}-21\frac{1}{2}=21\frac{5}{4}-21\frac{2}{4}=\frac{3}{4}$ inch