In figure, the optical fiber is $l=2\mathrm{m}$ long and has a diameter of $\mathrm{d}=20\mathrm{\mu m}$. If a ray of light is incident on one end of the fiber at angle ${\mathrm{\theta }}_1={40}^{\circ }$, the number of reflections it makes before emerging from the other end is close to:

(Refractive index of fiber is 1.31 and $\sin \left({40}^{\circ }\right)=0.64$)