Physics Question from JEE Main 2023 · 13 April, Shift 1

The radius of the $2^{\text{nd}}$ orbit of $He^+$ of Bohr's model is $r_1$ and that of the fourth orbit of $Be^{3+}$ is represented as $r_2$. Now the ratio $\frac{r_2}{r_1}$ is $x : 1$. The value of $x$ _____