This function and the graphed function both have 3 as the amplitude. However, they have different periods. The graphed function has a period of $\displaystyle\frac{{{2}\pi}}{{5}}\usepackage{cmbright}\Huge\$ , while $\displaystyle{y}={3}{\sin{{\left(\frac{{1}}{{5}}{x}\right)}}}\usepackage{cmbright}\Huge\$ has a period of $\displaystyle\frac{{{2}\pi}}{{\frac{{1}}{{5}}}}={10}\pi\usepackage{cmbright}\Huge\$ .