The electron in a hydrogen atom makes a transition ${n_1} \to {n_2}$ where ${n_1}$ and ${n_2}$ are the principal quantum numbers of the two states. Assume the Bohr model to be valid. The time period of electron in the initial state is ${\rm{8 }}\,{\rm{times}}$ that in the final state. The possible values of ${n_1}\,\,{\rm{and}}\,\,{n