a
$\frac{ L _{2}}{ T _{2}}=\frac{ n }{ m ^{2}} \frac{ L _{2}}{ T _{1}}$
$\frac{ L _{2}}{ T _{2}^{2}}=\frac{ L _{1}}{ T _{1}^{2} \times mn }$
$\frac{ n }{ m ^{2}} \times \frac{ T _{2}}{ T _{1}}=\frac{ T _{2}^{2}}{ T _{1}^{2} \times mn }$
$\frac{ n ^{2}}{ m }=\frac{ T _{2}}{ T _{1}}$
$\frac{ L _{2}}{ L _{1}}=\frac{ n ^{4}}{ m ^{2}} \times \frac{1}{ mn }$
$\frac{ L _{2}}{ L _{1}}=\frac{ n ^{5}}{ m ^{3}}$