As per given figure A, B and C are the first, second and third excited energy levels of hydrogen atom respectively. If the ratio of the two…

As per given figure $\displaystyle A, B$ and $\displaystyle C$ are the first, second and third excited energy levels of hydrogen atom respectively. If the ratio of the two wavelengths $\displaystyle \left(\right.$ i.e. $\displaystyle \left.\frac{\lambda_1}{\lambda_2}\right)$ is $\displaystyle \frac{7}{4 n}$, then the value of $\displaystyle n$ will be $\displaystyle \_\_\_\_$.