The wavelength is inversly proportional to frequency. So equation is,
[tex]\begin{gathered} \lambda\propto\frac{1}{\nu} \\ \lambda=\frac{k}{\nu} \end{gathered}[/tex]Determine the value of constant k.
[tex]\begin{gathered} 750=\frac{k}{100} \\ k=75000 \end{gathered}[/tex]Determine the frequency for wavelength of 2250.
[tex]\begin{gathered} 2250=\frac{75000}{\nu} \\ v=\frac{75000}{2250} \\ =33.333 \\ \approx33.3 \end{gathered}[/tex]